Removal of materials from water

ABSTRACT

Various embodiments relate to an electrochemical cell for removal of materials from water and methods of using the same. A method of removing phosphorus from water includes immersing an electrochemical cell in water including phosphorus to form treated water including a salt that includes the phosphorus. The electrochemical cell includes an anode including Mg, Al, Fe, Zn, or a combination thereof, a cathode including Cu, Ni, Fe, or a combination thereof. The method includes separating the salt including the phosphorus from the treated water, to form separated water having a lower phosphorus concentration than the water including phosphorus.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of International Application No.PCT/US2020/037405, filed Jun. 12, 2020, which claims the benefit ofpriority to U.S. Provisional Patent Application Ser. No. 62/860,433filed Jun. 12, 2019, the disclosure of each of which is incorporatedherein in their entireties by reference.

BACKGROUND

Phosphorus is a common constituent of agricultural fertilizers, manure,and organic wastes in sewage and industrial effluent. It is an essentialelement for plant life, but when there is too much of it in water, itcan cause growth of plants and algae and deplete oxygen from the waterat a rate that is greater than ecosystems can handle and can have severeecological effects including toxic algae blooms, death of native aquaticspecies, and loss of biodiversity (eutrophication). Although variousmethods for removal of phosphorus from water are available, existingmethods can be expensive, inconvenient, inefficient, lack scalability,or can be environmentally unfriendly.

SUMMARY OF THE INVENTION

Various embodiments of the present invention provide a method ofremoving phosphorus from water. The method includes immersing anelectrochemical cell in water including phosphorus to form treated waterincluding a salt that includes the phosphorus. The electrochemical cellincludes an anode including Mg, Al, Fe, Zn, or a combination thereof, acathode having a different composition than the anode, the cathodeincluding Cu, Ni, Fe, or a combination thereof. The method also includesseparating the salt including the phosphorus from the treated water, toform separated water having a lower phosphorus concentration than thewater including phosphorus.

Various embodiments of the present invention provide a method ofremoving phosphorus from water. The method includes immersing anelectrochemical cell in water including phosphorus having a pH of about5 to about 7 to form treated water including a salt that includes thephosphorus. The salt that includes the phosphorus includes AlPO₄ or ahydrate thereof, the AlPO₄ including the phosphorus and Al from theanode; aluminum hydroxide or a hydrate thereof, the aluminum hydroxideincluding Al from the anode; or a combination thereof. Theelectrochemical cell includes an anode including Al, wherein the anodeis about 90 wt % to about 100 wt % Al. The electrochemical cell includesa cathode including Cu, wherein the cathode is about 90 wt % to about100 wt % Cu. The electrochemical cell also includes a conductiveconnector that electrically connects the anode and the cathode, theconductive connector including an alloy including Cu and Zn. The methodalso includes separating the salt including the phosphorus from thetreated water, to form separated water having a lower phosphorusconcentration than the water including phosphorus.

Various embodiments of the present invention provide a method ofremoving phosphorus from water. The method includes immersing anelectrochemical cell in water including phosphorus having a pH of about10 to about 11 to form treated water including a salt that includes thephosphorus. The salt that includes the phosphorus includes magnesiumphosphate, magnesium potassium phosphate, a hydrate thereof, or acombination thereof, NH₄MgPO₄ or a hydrate thereof, the NH₄MgPO₄including the phosphorus and Mg from the anode; Mg(OH)₂ including Mgfrom the anode; or a combination thereof. The electrochemical cellincludes an anode including Mg, wherein the anode is about 90 wt % toabout 100 wt % Mg. The electrochemical cell includes a cathode includingCu, wherein the cathode is about 90 wt % to about 100 wt % Cu. Theelectrochemical cell also includes a conductive connector thatelectrically connects the anode and the cathode, the conductiveconnector including an alloy including Cu and Zn. The method alsoincludes separating the salt including the phosphorus from the treatedwater, to form separated water having a lower phosphorus concentrationthan the water including phosphorus.

Various embodiments of the present invention provide an electrochemicalcell for performing embodiments of the method described herein. Theelectrochemical cell includes a cathode including Cu, Ni, Fe, or acombination thereof, wherein the cathode includes a planar frame of theelectrochemical cell having a polygonal perimeter and a porous materialincluded within the perimeter of the frame that is a wire mesh or a wirescreen that is in direct contact with the frame. The electrochemicalcell also includes a plurality of anodes having a different compositionthan the cathode, the anodes including Mg, Al, Fe, Zn, or a combinationthereof, and a plurality of conductive connectors that electricallyconnect the anode and the cathode, the conductive connector includingCu, Zn, Fe, Cd, Ni, Sn, Pb, or a combination thereof. Each anode is astrip fastened to the planar frame at two opposite edges of the planarframe on a face of the frame, wherein each of the anodes is fastened tothe planar frame with at least one of the conductive connectors at eachof the two edges of the planar frame, such that each of the anodes onthe face are approximately parallel to one another on the face and spanacross the porous material included within the perimeter of the planarframe forming a gap between the porous material included within theperimeter of the planar frame and the anode strip. Each anode directlycontacts the cathode frame at each of the edges of the planar framewhere the anode is fastened to the planar frame via the at least oneconductive connector. The plurality of the anodes are spaced-apartacross the face of the such that they do not physically contact oneanother. The gap is about 1 mm to about 110 mm.

Various embodiments of the present invention provide a method of makingstruvite. The method includes immersing an electrochemical cell in waterincluding phosphorus having a pH of about 10 to about 11 to form treatedwater including a salt that includes the phosphorus. The salt thatincludes the phosphorus includes struvite, the struvite including thephosphorus and Mg from the anode. The electrochemical cell includes ananode including Mg, wherein the anode is about 90 wt % to about 100 wt %Mg. The electrochemical cell includes a cathode including Cu, whereinthe cathode is about 90 wt % to about 100 wt % Cu. The method alsoincludes separating the salt including the phosphorus from the treatedwater to obtain separated struvite and to form separated water having alower phosphorus concentration than the water including phosphorus.

Various embodiments of the present invention provide a method of makingAlPO₄, aluminum hydroxide, or a combination thereof. The method includesimmersing an electrochemical cell in water including phosphorus having apH of about 5 to about 7 to form treated water including a salt thatincludes the phosphorus. The salt that includes the phosphorus includesAlPO₄ or a hydrate thereof, the AlPO₄ including the phosphorus and Alfrom the anode; aluminum hydroxide or a hydrate thereof, the aluminumhydroxide including Al from the anode; or a combination thereof. Theelectrochemical cell includes an anode including Al, wherein the anodeis about 90 wt % to about 100 wt % Al. The electrochemical cell includesa cathode including Cu, wherein the cathode is about 90 wt % to about100 wt % Cu. The method includes separating the salt including thephosphorus from the treated water, to form separated water having alower phosphorus concentration than the water including phosphorus.

Various embodiments of the present invention provide a method of makingmagnesium phosphate, Mg(OH)₂, or a combination thereof. The methodincludes immersing an electrochemical cell in water including phosphorushaving a pH of about 10 to about 11 to form treated water including asalt that includes the phosphorus. The salt includes magnesiumphosphate, magnesium potassium phosphate, a hydrate thereof, or acombination thereof, Mg(OH)₂ including Mg from the anode; or acombination thereof. The electrochemical cell includes an anodeincluding Mg, wherein the anode is about 90 wt % to about 100 wt % Mg.The electrochemical cell includes a cathode including Cu, wherein thecathode is about 90 wt % to about 100 wt % Cu. The method also includesseparating the salt including the phosphorus from the treated water, toform separated water having a lower phosphorus concentration than thewater including phosphorus.

Various embodiments of the present invention provide a method ofremoving one or more dissolved transition metals, post-transitionmetals, or metalloids from water. The method includes immersing anelectrochemical cell in water including the one or more dissolvedtransition metals, post-transition metals, or metalloids to form treatedwater including a hydroxide salt that includes the one or moretransition metals, post-transition metals, or metalloids. Theelectrochemical cell includes an anode including Mg, Al, Fe, Zn, or acombination thereof. The electrochemical cell includes a cathodeincluding Cu, Ni, Fe, or a combination thereof. The method also includesseparating the salt including the hydroxide salt that includes the oneor more transition metals, post-transition metals, or metalloids, toform separated water having a lower concentration of the one or moretransition metals, post-transition metals, or metalloids than the waterincluding the one or more transition metals, post-transition metals, ormetalloids.

In various embodiments, the method of phosphorus removal of the presentinvention has certain advantages over other methods of removalphosphorus from water. For example, in some embodiments, the method ofphosphorus removal of the present invention can remove a larger amountof phosphorus, accomplish a lower concentration of phosphorus, achievephosphorus removal with greater efficiency or less cost, utilize asmaller footprint, or a combination thereof, as compared to othermethods.

In various embodiments, the method of phosphorus removal of the presentinvention can be performed with less oxidation of incoming water ascompared to other methods, or with no oxidation of incoming water. Insome embodiments that include an electrochemical cell including an anodethat includes Al, a higher pH near that anode from production ofhydroxide ions can induce or enhance precipitation of the aluminum salt(e.g., AlPO₄, aluminum hydroxide, or a combination thereof). In someembodiments, the ratio of Al to P used to remove the phosphorus from thewater is lower than those reported by other methods, such as methodsusing an addition of an aluminum salt.

BRIEF DESCRIPTION OF THE FIGURES

The drawings illustrate generally, by way of example, but not by way oflimitation, various embodiments of the present invention.

FIG. 1A illustrates an electrochemical cell view from a major face, inaccordance with various embodiments.

FIG. 1B illustrates a zoomed-in cutaway edge view of an electrochemicalcell, according to various embodiments.

FIG. 2A illustrates a photograph along the edge of an Al—Cuelectrochemical cell, in accordance with various embodiments.

FIG. 2B illustrates a photograph along an edge of a plurality of Al—Cuelectrochemical cells, in accordance with various embodiments.

FIG. 2C illustrates a photograph of a major face of a Mg—Cuelectrochemical cell, in accordance with various embodiments.

FIG. 2D illustrates a photograph of an edge of a Mg—Cu electrochemicalcell, in accordance with various embodiments.

FIG. 2E illustrates a photograph of an edge of a Mg—Cu electrochemicalcell, in accordance with various embodiments.

FIG. 2F illustrates a photograph showing a top view of a system forremoving materials from water, in accordance with various embodiments.

FIG. 2G illustrates a photograph showing a side-view of a system forremoving materials from water, in accordance with various embodiments.

FIG. 3 illustrates electrical current generated by an Al—Cu cell versustime for solutions having various conductivities, in accordance withvarious embodiments.

FIG. 4 illustrates electrical current generated by an Al—Cu cell versustime for solutions having various pH levels, in accordance with variousembodiments.

FIG. 5A illustrates electrical current generated by an Mg—Cu cell versustime for solutions having various conductivities, in accordance withvarious embodiments.

FIG. 5B illustrates electrical current generated by an Mg—Cu cell versustime for solutions having various pH levels, in accordance with variousembodiments.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to certain embodiments of thedisclosed subject matter. While the disclosed subject matter will bedescribed in conjunction with the enumerated claims, it will beunderstood that the exemplified subject matter is not intended to limitthe claims to the disclosed subject matter.

Throughout this document, values expressed in a range format should beinterpreted in a flexible manner to include not only the numericalvalues explicitly recited as the limits of the range, but also toinclude all the individual numerical values or sub-ranges encompassedwithin that range as if each numerical value and sub-range is explicitlyrecited. For example, a range of “about 0.1% to about 5%” or “about 0.1%to 5%” should be interpreted to include not just about 0.1% to about 5%,but also the individual values (e.g., 1%, 2%, 3%, and 4%) and thesub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within theindicated range. The statement “about X to Y” has the same meaning as“about X to about Y,” unless indicated otherwise. Likewise, thestatement “about X, Y, or about Z” has the same meaning as “about X,about Y, or about Z,” unless indicated otherwise.

In this document, the terms “a,” “an,” or “the” are used to include oneor more than one unless the context clearly dictates otherwise. The term“or” is used to refer to a nonexclusive “or” unless otherwise indicated.The statement “at least one of A and B” or “at least one of A or B” hasthe same meaning as “A, B, or A and B.” In addition, it is to beunderstood that the phraseology or terminology employed herein, and nototherwise defined, is for the purpose of description only and not oflimitation. Any use of section headings is intended to aid reading ofthe document and is not to be interpreted as limiting; information thatis relevant to a section heading may occur within or outside of thatparticular section.

In the methods described herein, the acts can be carried out in anyorder without departing from the principles of the invention, exceptwhen a temporal or operational sequence is explicitly recited.Furthermore, specified acts can be carried out concurrently unlessexplicit claim language recites that they be carried out separately. Forexample, a claimed act of doing X and a claimed act of doing Y can beconducted simultaneously within a single operation, and the resultingprocess will fall within the literal scope of the claimed process.

The term “about” as used herein can allow for a degree of variability ina value or range, for example, within 10%, within 5%, or within 1% of astated value or of a stated limit of a range, and includes the exactstated value or range. The term “substantially” as used herein refers toa majority of, or mostly, as in at least about 50%, 60%, 70%, 80%, 90%,95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999%or more, or 100%. The term “substantially free of” as used herein canmean having none or having a trivial amount of, such that the amount ofmaterial present does not affect the material properties of thecomposition including the material, such that about 0 wt % to about 5 wt% of the composition is the material, or about 0 wt % to about 1 wt %,or about 5 wt % or less, or less than or equal to about 4.5 wt %, 4,3.5, 3, 2.5, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1,0.01, or about 0.001 wt % or less, or about 0 wt %.

In various embodiments, salts having a positively charged counterion caninclude any suitable positively charged counterion. For example, thecounterion can be ammonium (NH₄ ⁺), or an alkali metal such as sodium(Na⁺), potassium (K⁺), or lithium (Li⁺). In some embodiments, thecounterion can have a positive charge greater than +1, which can in someembodiments complex to multiple ionized groups, such as Zn²⁺, Al³⁺, oralkaline earth metals such as Ca²⁺ or Mg²⁺.

All concentrations of phosphorus, magnesium, and aluminum referred toare dissolved concentrations of these materials in elemental ornon-elemental (e.g., as a compound or ion including the material) forms,unless otherwise indicated. All concentrations given herein are byweight unless otherwise indicated.

As used herein, “total phosphorus concentration” refers to theconcentration of all forms of phosphorus, as measured by US-EPA 365.1:Determination of Phosphorus by Semi-Automated Colorimetry or equivalent,unless otherwise indicated.

As used herein, “dissolved phosphorus concentration” refers to theconcentration of all forms of phosphorus passable though a 0.45 micronfilter and as measured by US-EPA 365.1: Determination of Phosphorus bySemi-Automated Colorimetry or equivalent, unless otherwise indicated.

As used herein, “reactive phosphorus concentration” refers to thesoluble reactive phosphorus in solution (e.g., orthophosphate) asmeasured by US-EPA 365.1: Determination of Phosphorus by Semi-AutomatedColorimetry or equivalent unless otherwise indicated.

Method of Removing Phosphorus from Water.

In various embodiments, the present invention provides a method ofremoving phosphorus from water. The phosphorus can be removed in theform of a salt including the phosphorus using an electrochemical cell(e.g., one or more electrochemical cells). The method can includeimmersing an electrochemical cell in water including phosphorus to formtreated water including a salt that includes the phosphorus. Theelectrochemical cell can include an anode including Mg, Al, Fe, Zn, or acombination thereof. The electrochemical cell can include a cathodeincluding Cu, Ni, Fe, or a combination thereof. The method can alsoinclude separating the salt including the phosphorus from the treatedwater, to form separated water having a lower phosphorus concentrationthan the water including phosphorus. In some embodiments, theelectrochemical cell can also include a conductive connector thatelectrically connects the anode and the cathode, the conductiveconnector including Cu, Zn, Fe, Cd, Ni, Sn, Pb, or a combinationthereof. In some embodiments, the anode and the cathode can directlycontact one another and the electrochemical cell can be free of theconductive connectors.

The electrochemical cell can be a galvanic cell. The method can be freeof applying electrical potential (e.g., applied potential from a sourceexternal to the electrochemical cell) across the anode and the cathodeof the electrochemical cell. In some embodiments, the electrochemicalcell can be an electrolytic cell. The method can include applying anelectrical potential across the anode and the cathode of theelectrochemical cell. The applied potential can be greater than thegalvanic corrosion potential of the electrochemical cell (e.g., thepotential the anode and cathode reach with no external potential appliedthereto when immersed in the water including phosphorus). The appliedpotential can be less than the galvanic corrosion potential of theelectrochemical cell. The applied potential can be equal to the galvaniccorrosion potential of the electrochemical cell.

The method can include immersing an electrochemical cell in waterincluding phosphorus. The immersing of the electrochemical cell in thewater including phosphorus can include partial immersion, such that anysuitable proportion of the surface area of the electrochemical cell isin contact with the water, such as about 1% to about 100%, 80% to about100%, or less than, equal to, or greater than about 1%, 10, 20, 30, 40,50, 60, 70, 80, 90, 95, 96, 97, 98, or about 99% or more. The immersingof the electrochemical cell in the water including phosphorus caninclude complete immersion, such that about 100% of the surface area ofthe electrochemical cell is in contact with the water.

The water including phosphorus can be taken from any suitable source.For example, the water including phosphorus can be taken from a sourceincluding a natural source of water in the environment, drinking water(e.g., for removal of struvite to prevent formation in pipes),industrial waste-water, industrial cooling water, or a combinationthereof. The water including phosphorus can be water taken from a sourceincluding a natural source of water in the environment, such as a pond,lake, river, stream, and the like. In some embodiments, the method caninclude taking the water from the source, returning the water to thesource after removal of phosphorus, or a combination thereof.

The phosphorus in the water including the phosphorus can be in anysuitable form. For example, the phosphorus can be in the form ofelemental phosphorus, inorganic phosphorus, organic phosphorus, adissolved form of phosphorus, a solid form of phosphorus, oxidizedphosphorus, or a combination thereof. The water including the phosphoruscan have a total phosphorus concentration, a dissolved phosphorusconcentration, a reactive phosphorus concentration, or a combinationthereof, of about 0.001 ppm to about 10,000 ppm, about 0.01 ppm to about20 ppm, or about 0.001 ppm or less, or less than, equal to, or greaterthan about 0.005 ppm, 0.01, 0.02, 0.04, 0.06, 0.08, 0.1, 0.15, 0.2, 0.4,0.6, 0.8, 1, 2, 4, 6, 8, 10, 15, 20, 40, 60, 80, 100, 150, 200, 400,600, 800, 1,000, 1,500, 2,000, 4,000, 6,000, 8,000, or about 10,000 ppmor more.

The separated water can have a total phosphorus concentration, adissolved phosphorus concentration, a reactive phosphorus concentration,or a combination thereof, of about 0 ppm to about 1 ppm, about 0.0001ppm to 0.1 ppm, about 0.0001 ppm to 0.05 ppm, or about 0 ppm, or lessthan, equal to, or greater than about 0.0001 ppm, 0.0002, 0.0004,0.0006, 0.0008, 0.0010, 0.0012, 0.0014, 0.0016, 0.0018, 0.0020, 0.0022,0.0024, 0.0026, 0.0028, 0.0030, 0.0032, 0.0034, 0.0036, 0.0038, 0.0040,0.0045, 0.0050, 0.0060, 0.0080, 0.01, 0.02, 0.04, 0.06, 0.08, 0.1, 0.2,0.4, 0.6, 0.8, or about 1.0 ppm or more. The separated water can have atotal phosphorus concentration, a dissolved phosphorus concentration, areactive phosphorus concentration, or a combination thereof, that isabout 0% to 70% of the respective total phosphorus concentration, adissolved phosphorus concentration, a reactive phosphorus concentration,or a combination thereof, of the water including the phosphorus that isinitially contacted with the electrochemical cell, or about 0% to about20%, or about 0%, or less than, equal to, or greater than about 0.001%,0.005, 0.01, 0.05, 0.1, 0.5, 1, 2, 4, 6, 8, 10, 15, 20, 25, 30, 35, 40,45, 50, 55, 60, 65, or about 70% or more.

During the immersing of the electrochemical cell in the water includingthe phosphorus, the water including phosphorus can have any suitable pH.The pH can be about 2 to about 14, about 5 to about 11, about 5 to about7, about 10 to about 11, or less then, equal to, or greater than about2, 2.5, 3, 3.5, 4, 4.5, 5, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9,6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7, 7.5, 8, 8.5, 9, 9.5,10, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11, 11.5, 12,12.5, 13, 13.5, or about 14 or more.

The method can include adding acid, base, or a combination thereof tothe water including phosphorus to adjust or control the pH thereof. Insome embodiments, the method is free of adding acid, base, or acombination thereof to the water including phosphorus. The acid, base,or combination thereof can be added to the water including phosphorusbefore the immersing of the electrochemical cell in the water includingphosphorus, during the immersing of the electrochemical cell in thewater including phosphorus, after the immersing of the electrochemicalcell in the water including phosphorus, or a combination thereof.

The method can include recirculating the water including phosphorus thatimmerses the electrochemical cell to contact the water includingphosphorus with the electrochemical cell multiple times. The water canoptionally be filtered during the recirculation, such as to remove saltincluding phosphorus from the water.

Immersing an electrochemical cell in water including phosphorus can formtreated water including a salt that includes the phosphorus. Contactbetween the water including the phosphorus and the electrochemical cellcan cause formation of the salt that includes the phosphorus. At leastsome of the salt including the phosphorus in the treated water caninclude a solid. Formation of the solid including the phosphorus caninclude precipitation, flocculation, or a combination thereof.

Separating the salt including the phosphorus from the treated water, toform separated water having a lower phosphorus concentration than thewater including phosphorus, can be performed in any suitable way. Theseparating can include decantation, settling, filtration, or acombination thereof. The separating can include separating the treatedwater from the electrochemical cell (e.g., removing water immersing thecell that has been filtered or from which the salt including thephosphorus has otherwise been separated). The separation can occurduring a recirculation of the water back to the electrochemical cell.The separation can be performed during the contacting theelectrochemical cell with the water, such as via a filter that isimmersed in the water and is continuously filtering the water during thecontacting. The separation can occur after the water is removed from thewater that immerses the electrochemical cell, such as via a filter on anexit line out of the system. The filtration can be conducted using aglass frit, a fabric filter, a paper filter, a disk filter, a rotaryfilter, a drum filter, a screen, a sieve, particulate filtration media,a filter aid, or a combination thereof. The separated water can beoptionally further treated, such as via further contact with the same ordifferent electrochemical cell, filtration, treatment to remove one ormore other non-phosphorus materials, pH adjusted, or a combinationthereof.

The anode can be a sacrificial anode that is consumed during treatmentof the water including the phosphorus. The salt including the phosphorusthat is formed upon contact of the water including the phosphorus withthe electrochemical cell can include a material from the anode. Themethod can include forming a hydroxide salt including a material fromthe anode during the immersing of the electrochemical cell in the waterincluding phosphorus. Separating the salt including the phosphorus fromthe treated water can further include separating the hydroxide saltincluding the material from the anode from the treated water.

The water including phosphorus can further include a dissolvedtransition metal, post-transition metal, metalloid, or a combinationthereof. The method can include forming a hydroxide salt including thetransition metal, post-transition metal, or metalloid during theimmersing of the electrochemical cell in the water including phosphorus.Separating of the salt including the phosphorus from the treated watercan include separating the hydroxide salt including the transitionmetal, post-transition metal, or metalloid from the treated water. Thetransition metal, post-transition metal, or metalloid can be Sc, Y, Ti,V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta, W,Re, Os, Ir, Pt, Au, Rf, Db, Sg, Bh, Hs, Al, Zn, Ga, Cd, In, Sn, Hg, Tl,Pb, Bi, Po, Cn, B, Si, Ge, As, Sb, Te, At, or a combination thereof. Thetransition metal, post-transition metal, or metalloid can be Hg, Fe, Cr,Ni, Zn, Cd, As, or a combination thereof. The method can remove anysuitable amount of the transition metal, post-transition metal,metalloid, or combination thereof from the water. The separated watercan have a concentration of the transition metal, post-transition metal,metalloid, or combination thereof, that is about 0% to about 70% of aconcentration of the transition metal, post-transition metal, metalloid,or combination thereof, in the water including the one or more dissolvedtransition metals, post-transition metals, or metalloids, or about 0% toabout 20%, or about 0%, or about 1% or less, or less than, equal to, orgreater than about 2%, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,17, 18, 19, 20, 22, 24, 26, 28, 30, 35, 40, 45, 50, 55, 60, 65, or about70% or more of a concentration of the transition metal, post-transitionmetal, metalloid, or combination thereof, in the water including the oneor more dissolved transition metals, post-transition metals, ormetalloids.

The method can include forming H₂ and HO⁻ at the anode (e.g., generateon the surface of the anode, from water) during the immersing of theelectrochemical cell in the water including phosphorus. The method caninclude forming H₂ and HO⁻ at the cathode (e.g., generate on the surfaceof the cathode, from water) during the immersing of the electrochemicalcell in the water including phosphorus. The method can include formingH₂O₂, HO₂ ⁻, or a combination thereof at the cathode (e.g., generate onthe surface of the cathode) during the immersing of the electrochemicalcell in the water including phosphorus. The method can include applyingshear to the water including the phosphorus during the immersing of theelectrochemical cell in the water including phosphorus. The shear can besufficient to dislodge at least some bubbles (e.g., including H₂) fromthe surface of the anode, cathode, or a combination thereof. The shearcan be sufficient to at least partially prevent or reduce oxideformation at the surface of the anode. The method can include applying amechanical force to the electrochemical cell immersed in the waterincluding phosphorus, such as a rapping, knocking, agitating, vibration,ultrasound, and the like. The mechanical force can be sufficient todislodge at least some bubbles including H₂ from the surface of theanode, cathode, or a combination thereof; at least partially preventoxide formation at the surface of the anode; at least partially preventagglomeration of the salt including the phosphorus on the surface of theanode; or a combination thereof.

The water including phosphorus can further include nitrogen. Thenitrogen in the water including phosphorus can be in any suitable form,such as in the form of elemental nitrogen, inorganic nitrogen, organicnitrogen, a dissolved form of nitrogen, a solid form of nitrogen,oxidized nitrogen, or a combination thereof. The total nitrogenconcentration, dissolved nitrogen concentration, or a combinationthereof, of the water including phosphorus can be about 0.001 ppm toabout 20 ppm, about 1 ppm to about 5 ppm, or about 0.001 ppm or less, orless than, equal to, or greater than about 0.005 ppm, 0.01, 0.02, 0.04,0.06, 0.08, 0.1, 0.15, 0.2, 0.4, 0.6, 0.8, 1, 2, 4, 6, 8, 10, 12, 14,16, 18, or about 20 ppm or more. The separated water can have a totalnitrogen concentration, a dissolved nitrogen concentration, or acombination thereof, of about 0 ppm to about 2 ppm, about 0 ppm to about1 ppm, or about 0 ppm, or less than, equal to, or greater than 0.001ppm, 0.0012, 0.0014, 0.0016, 0.0018, 0.0020, 0.0022, 0.0024, 0.0026,0.0028, 0.0030, 0.0032, 0.0034, 0.0036, 0.0038, 0.0040, 0.0045, 0.0050,0.0060, 0.0080, 0.01, 0.02, 0.04, 0.06, 0.08, 0.1, 0.2, 0.4, 0.6, 0.8,1, 1.1, 1.2, 1.4, 1.6, 1.8, or about 2 ppm or more. The separated watercan have a total nitrogen concentration, a dissolved nitrogenconcentration, or a combination thereof, that is about 0% to about 70%of the respective total nitrogen concentration, dissolved nitrogenconcentration, or a combination thereof, of the water includingphosphorus, or about 0% to about 30%, or about 0%, or less than, equalto, or greater than about 0.001%, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 2, 4,6, 8, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, or about 70% ormore.

The method can further include forming NH₃, NH₄ ⁺, or a combinationthereof, at the cathode (e.g., at the surface of the cathode), whereinthe NH₃ and NH₄ ⁺ include the nitrogen from the water includingphosphorus. The method can include forming a salt including the nitrogenduring the immersing of the electrochemical cell in the water includingphosphorus. The separating of the salt including the phosphorus from thetreated water can include separating the salt including the nitrogenfrom the treated water. The salt including the nitrogen can includeNH₄MgPO₄ or a hydrate thereof (e.g., struvite).

The cathode of the electrochemical cell can include Cu, Ni, Fe, or acombination thereof, such as Cu or a Cu alloy. The cathode can be asolid material that is predominantly Cu, Ni, Fe, alloys thereof, or acombination thereof, or another material that is coated withpredominantly Cu, Ni, Fe, alloys thereof, or a combination thereof. Thecathode can be substantially free of materials other than Cu, Ni, Fe,alloys thereof, or a combination thereof. The cathode can be about 50 wt% to about 100 wt % Cu, Ni, Fe, alloys thereof, or a combinationthereof, about 90 wt % to about 100 wt %, or less than, equal to, orgreater than about 50 wt %, 55, 60, 65, 70, 75, 80, 82, 84, 86, 88, 90,91, 92, 93, 94, 95, 96, 97, 98, 99, 99.5, 99.9, 99.99, or about 99.999wt % or more. In some embodiments, the cathode includes Cu and the anodeincludes Mg. In some embodiments, the cathode includes Cu and the anodeincludes Al.

The anode can be a solid material of approximately homogeneouscomposition or can be a coating on another material. The anode has adifferent composition than the cathode. The anode can include Mg, Al,Fe, Zn, or a combination thereof. The anode can include an alloy thatincludes Mg, Al, Fe, Zn, or an alloy thereof. The Mg, Al, Fe, Zn, alloysthereof, or combinations thereof, can be about 50 wt % to about 100 wt %of the anode, or less than, equal to, or greater than about 50 wt %, 55,60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, or about 99,99.5, 99.9, 99.99, or about 99.999 wt % or more. The anode can besubstantially free of materials other than Mg, Al, Fe, Zn, alloysthereof, or combinations thereof.

The anode can further include Ag, Pt, Au, or a combination thereof. TheAg, Pt, Au, or the combination thereof is about 0.0001 wt % to about 20wt %, about 0.0001 wt % to about 5 wt %, or about 0 wt %, or about0.0001 wt % or less, or 0.0002, 0.0004, 0.0006, 0.0008, 0.0010, 0.0012,0.0014, 0.0016, 0.0018, 0.0020, 0.0022, 0.0024, 0.0026, 0.0028, 0.0030,0.0032, 0.0034, 0.0036, 0.0038, 0.0040, 0.0045, 0.0050, 0.0060, 0.0080,0.01, 0.02, 0.04, 0.06, 0.08, 0.1, 0.2, 0.4, 0.6, 0.8, 1, 1.5, 2, 4, 6,8, 10, 12, 14, 16, 18, or about 20 wt % or more.

The anode can include Mg or an Mg alloy. The anode can be substantiallyfree of materials other than Mg or alloys thereof. The anode can bemagnesium alloy AZ91 that is about 90 wt % Mg, about 9 wt % Al, andabout 1 wt % Zn. The anode can be about 50 wt % to about 100 wt % Mg orMg alloy, about 90 wt % to about 100 wt % Mg or Mg alloy, or less than,equal to, or greater than about 50 wt %, 55, 60, 65, 70, 75, 80, 85, 90,91, 92, 93, 94, 95, 96, 97, 98, 99, 99.5, 99.9, 99.99, or about 99.999wt % Mg or Mg alloy or more. The salt including the phosphorus caninclude magnesium phosphate, magnesium potassium phosphate (e.g.,“K-struvite”), a hydrate thereof, or a combination thereof, wherein themagnesium phosphate or magnesium potassium phosphate includes Mg fromthe anode. The magnesium phosphate can be in any suitable form, such asmonomagnesium phosphate (Mg(H₂PO₄)₂), dimagnesium phosphate (MgHPO₄),trimagnesium phosphate (Mg₃(PO₄)₂), a hydrate thereof, or a combinationthereof. The separating of the salt including the phosphorus from thetreated water can include separating the magnesium phosphate from thetreated water. The water including phosphorus can further includesnitrogen, wherein the salt including the phosphorus includes NH₄MgPO₄ ora hydrate thereof (e.g., struvite), with the NH₄MgPO₄ including thephosphorus and Mg from the anode. The method can include forming Mg(OH)₂including Mg from the anode during the immersing of the electrochemicalcell in the water including phosphorus. The separating of the saltincluding the phosphorus from the treated water can include separatingthe Mg(OH)₂ from the treated water. During the immersing of theelectrochemical cell in the water including the phosphorus, the waterincluding the phosphorus can have a pH of about 9.5 to about 11.5, orabout 10 to about 11, or less than, equal to, or greater than 9.5, 9.6,9.7, 9.8, 9.9, 10.0, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8,10.9, 11.0, 11.1, 11.2, 11.3, 11.4, or about 11.5 or more. The methodcan include regulating a rate of introduction of fresh water includingthe phosphorus to the electrochemical cell such that the water includingthe phosphorus that immerses the electrochemical cell is maintaining ata pH of about 9.5 to about 11.5, or about 10 to about 11, or less than,equal to, or greater than 9.5, 9.6, 9.7, 9.8, 9.9, 10.0, 10.1, 10.2,10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11.0, 11.1, 11.2, 11.3, 11.4,or about 11.5 or more. The method can include immersing theelectrochemical cell in the water including the phosphorus until thewater including the phosphorus reaches a pH of about 9.5 to about 11.5or about 10 to about 11, and then regulating a rate of introduction offresh water including the phosphorus to the electrochemical cell suchthat the water including the phosphorus that immerses theelectrochemical cell is maintained at a pH of about 9.5 to about 11.5 orabout 10 to about 11.

The anode can include Al. The anode can be substantially free ofmaterials other than Al. The anode can be about 50 wt % to about 100 wt% Al, about 90 wt % to about 100 wt % Al, or less than, equal to, orgreater than about 50 wt %, 55, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93,94, 95, 96, 97, 98, or about 99, 99.5, 99.9, 99.99, or about 99.999 wt %or more. The salt including phosphorus can include AlPO₄ or a hydratethereof. Separating of the salt including the phosphorus from thetreated water can include separating the AlPO₄ from the treated water.The method can include forming aluminum hydroxide or a hydrate thereof(e.g., Al(OH)₃ or polyaluminum hydroxide), the aluminum hydroxideincluding Al from the anode during the immersing of the electrochemicalcell in the water including phosphorus. Separating of the salt includingthe phosphorus from the treated water can include separating thealuminum hydroxide from the treated water. During the immersing of theelectrochemical cell in the water including the phosphorus, the waterincluding phosphorus has a pH of about 4 to about 8, about 5 to about 7,or about 4 or less, or about 4.2, 4.4, 4.6, 4.8, 5, 5.1, 5.2, 5.3, 5.4,5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8,6.9, 7, 7.2, 7.4, 7.6, 7.8, or about 8 or more. The method can includeregulating a rate of introduction of an acid to the water including thephosphorus such that the water including the phosphorus that immersesthe electrochemical cell is maintained at a pH of about 4 to about 8,about 5 to about 7, or about 4 or less, or about 4.2, 4.4, 4.6, 4.8, 5,5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4,6.5, 6.6, 6.7, 6.8, 6.9, 7, 7.2, 7.4, 7.6, 7.8, or about 8 or more. Theacid can be added to the water including the phosphorus prior to theimmersion of the electrochemical cell in the water including thephosphorus, during the immersion of the electrochemical cell in thewater including the phosphorus, after the immersion of theelectrochemical cell in the water including the phosphorus, or acombination thereof. The acid can be any suitable acid, at any suitableconcentration. The acid can include sulfuric acid, acetic acid,hydrochloric acid, or a combination thereof. The method can includeflocculating salts that include Al from the treated water.

The cathode can have a work function that is larger than the workfunction of the anode. For example, Cu has a work function of about4.53-5.10 eV, Mg has a work function of about 3.66 eV, and Al has a workfunction of about 4.06-4.26 eV. The conductive connector can have a workfunction that is between the work function of the cathode and the workfunction of the cathode.

The electrochemical cell can include a conductive connector thatelectrically connects the anode and the cathode. The conductiveconnector has a different composition than the anode or the cathode. Theconductive connector can be a solid material with a homogeneouscomposition or can be a coating on another material. The conductiveconnector can include Cu, Zn, Fe, Cd, Ni, Sn, Pb, or a combinationthereof. The conductive connector can include Cu. The conductiveconnector can include Zn. The conductive connector can include an alloyincluding Cu and Zn. The conductive connector can include brass. Theconductive connector can include brass, and can be substantially free ofother materials. The conductive connector can be about 50 wt % to about100 wt % brass, about 90 wt % to about 100 wt %, or less than, equal to,or greater than about 50 wt %, 55, 60, 65, 70, 75, 80, 85, 90, 91, 92,93, 94, 95, 96, 97, 98, or about 99, 99.5, 99.9, 99.99, or about 99.999wt % or more.

The water including the phosphorus can have any suitable conductivityduring immersion of the electrochemical cell in the water including thephosphorus, such as about 100 μS to about 1,000,000 μS, or about 300 μSto about 100,000 μS, or about 100 μS to about 1,200 μS, or less than,equal to, or greater than about 100 μS, 200, 300, 400, 500, 600, 700,800, 900, 1,000, 1,100, 1,200, 1,500, 2,000, 4,000, 6,000, 10,000,15,000, 20,000, 50,000, 100,000, 150,000, 200,000, 250,000, 500,000,750,000, or about 1,000,000 μS or more. The method can be free ofregulation of the conductivity of the water including the phosphorus. Insome embodiments, the method can include regulating the conductivity ofthe water including phosphorus such that the conductivity is maintainedat about 100 μS to about 1,000,000 μS, or about 300 μS to about 100,000μS, or about 100 μS to about 1,200 μS, or less than, equal to, orgreater than about 100 μS, 200, 300, 400, 500, 600, 700, 800, 900,1,000, 1,100, 1,200, 1,500, 2,000, 4,000, 6,000, 10,000, 15,000, 20,000,50,000, 100,000, 150,000, 200,000, 250,000, 500,000, 750,000, or about1,000,000 μS or more. Regulating the conductivity of the water includingthe phosphorus can include regulating a rate of introduction of freshwater including the phosphorus to the electrochemical cell. Regulatingthe conductivity of the water including the phosphorus can includeadding one or more salts to the water including the phosphorus. The saltcan be added to the water including the phosphorus before immersing theelectrochemical cell in the water including phosphorus, during theimmersion of the electrochemical cell in the water including phosphorus,after the immersion of the electrochemical cell in the water includingphosphorus, or a combination thereof. The one or more salts added to thewater including phosphorus to regulate the conductivity thereof caninclude halogen salts, sodium salts, potassium salts, or a combinationthereof. The one or more salts added to the water including phosphorusto regulate the conductivity thereof can include sodium chloride.

The electrochemical cell can generate a current when immersed in thewater including the phosphorus. The amount of current generated by theelectrical cell can be any suitable amount of current, such as about0.001 mA/cm² to about 10 mA/cm², 0.01 mA/cm² to about 0.5 mA mA/cm², orless than, equal to, or greater than about 0.001 mA/cm², 0.005, 0.01,0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.06, 0.07, 0.08,0.09, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.7, 0.8,0.9, 1, 1.2, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, or about 10 mA/cm² ormore.

The immersing of the electrochemical cell in the water including thephosphorus can be sufficient to oxidize the phosphorus in the waterincluding the phosphorus. The method can be free of treating the waterincluding the phosphorus with an oxidizer or an oxidative treatmentother than any oxidation that occurs due to immersion of theelectrochemical cell in the water including the phosphorus. In someembodiments, the method includes oxidizing phosphorus in the waterincluding the phosphorus prior to the immersion of the electrochemicalcell in the water including phosphorus, during the immersion of theelectrochemical cell in the water including phosphorus, or a combinationthereof. The method can include oxidizing phosphorus in the waterincluding the phosphorus prior to the immersion of the electrochemicalcell in the water including phosphorus. Oxidizing the phosphorus in thewater including the phosphorus can include contacting an oxidizer andthe water including phosphorus to oxidize the phosphorus (e.g., tooxidize phosphorus in organic matter or solid matter that containsphosphorus). An aqueous solution of the oxidizer can be added to thewater including phosphorus. The aqueous solution of the oxidizer has aconcentration of the oxidizer of about 0.001 ppm to about 999,999 ppm,about 50,000 ppm to about 140,000 ppm, or less than, equal to, orgreater than about 0.001 ppm, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 1.5, 2, 5,10, 15, 20, 50, 100, 150, 200, 500, 1,000, 1,100, 1,200, 1,500, 2,000,2,500, 5,000, 10,000, 15,000, 20,000, 50,000, 100,000, 150,000, 200,000,500,000, 750,000, or about 999,999 ppm or more. The oxidizer can be anysuitable oxidizer that oxidizes the phosphorus. The oxidizer can includeferrate, ozone, ferric chloride (FeCl₃), potassium permanganate,potassium dichromate, potassium chlorate, potassium persulfate, sodiumpersulfate, perchloric acid, peracetic acid, potassium monopersulfate,hydrogen peroxide, sodium hypochlorite, potassium hypochlorite,hydroxide, sulfite, a free radical via decomposition thereof, or acombination thereof. Sufficient oxidizer can be added, and sufficienttreatment conditions used, such that the oxidizer converts substantiallyall dissolved phosphorus in the water including the phosphorus intooxidized forms of phosphorus.

Byproducts of an oxidation process can include negatively charged ioniccompounds that readily accept electrons and as a result arepreferentially reduced at the surface of copper in the galvanic cell.Many of these compounds have very low regulatory limits, and thegalvanic process can be used to remove or reduce the concentration ofone or more of these highly regulated compounds prior to the dischargeor reuse of the treated water. Examples of the most common compoundsthat can be reduced or removed are chloramines, chlorates, perchlorates,bromates, hypochlorous acid, bleach, and the like, organic compounds,and combinations thereof. Further, the galvanic process can reduce theoxygen levels in the water to values below 1 ppm, thus creatingattractive condition for subsequent anoxic or anaerobic processes.

The method can be free of performing any steps to adjust pH of thetreated water. In some embodiments, the method can include adjusting thepH of the separated water to be about 6 to 8, or about 7, or less than,equal to, or greater than about 6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7,6.8, 6.9, 7, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, or about 8 ormore.

The method can include immersing one or more of the electrochemicalcells in an enclosure including the water including the phosphorus. Themethod can include filtering the salt including the phosphorus from thetreated water via one of more filters that are at least partiallysubmerged in the water including the phosphorus that immerses theelectrochemical cells. The filter can include a glass frit, a fabricfilter, a paper filter, a disk filter, a rotary filter, a drum filter, ascreen, a sieve, particulate filtration media, a filter aid, or acombination thereof. The filter can be a rotating disk filter. Thefiltering can include forming a filter cake on the filter, the filtercake including the salt including the phosphorus. The filtering caninclude backwashing the filter to remove the filter cake from the filterand to form a backwash liquor that includes the removed filter cake. Anysuitable water can be used to backwash the filter, such as a portion ofthe water including the precipitate is used to backwash the filter.

The one or more electrochemical cells can be positioned in the waterincluding the phosphorus at side portions of the enclosure, wherein thefilter is positioned approximately in a central portion of the enclosurein the water including the phosphorus such that the filter is in-betweenthe plurality of electrochemical cells. The method can include using aplurality of filters. The plurality of filters can include a pluralityof rotating disk filters.

In embodiments of the galvanic cell including aluminum in the anode, thedissolution of the aluminum anode during the operation of the galvaniccell can generate high localized concentrations of aluminum ions on orvery near the surface of the electrode which can favor thesupersaturation and thermodynamic conditions for the precipitation ofaluminum phosphate compounds. This surface condition can create a lowmetal-to-phosphorus molar ratio, even when phosphorus levels in waterare below 0.1 ppm. The resulting equilibrium concentration of phosphateremaining in solution can be much lower than those obtained by simplyadding aluminum salts to the water. When adding aluminum salts tophosphate-containing waters with the intent to obtain phosphorousconcentrations below about 0.1 ppm, the metal-to-phosphorus molar ratiosmust be close to 8. In contrast, in the galvanic process describedherein, the molar ratio of metal to phosphorus can be less than 8, suchas approximately 1.

Electrochemical Cell.

In various embodiments the present invention provides an electrochemicalcell. The electrochemical cell can be any suitable electrochemical cellthat can be used to perform an embodiment of the method describedherein. The method of removing phosphorus from water can includeimmersing an electrochemical cell (e.g., one or more electrochemicalcells) in water including phosphorus to form treated water including asalt that includes the phosphorus. The electrochemical cell can includean anode including Mg, Al, Fe, Zn, or a combination thereof. Theelectrochemical cell can include a cathode including Cu, Ni, Fe, or acombination thereof.

The electrochemical cell can also include a conductive connector thatelectrically connects the anode and the cathode, the conductiveconnector including Cu, Zn, Fe, Cd, Ni, Sn, Pb, or a combinationthereof. In some embodiments, the anode and the cathode directly contactone another and the electrochemical cell is free of the conductiveconnector, such that the electrodes are in an “electroless”configuration. In an electroless configuration, the sacrificial anodematerial can be electrochemically plated or deposited on thenon-sacrificial cathode material, eliminating a need for conductiveconnectors to electrically connect the anode and the cathode. Oneadvantage of various embodiments of the electroless configuration isthat less metallic copper can be used and the electric drop between theelectrodes can decrease compared to the configuration includingconductive connectors.

The electrochemical cell can include one cathode, or a plurality ofcathodes. The electrochemical cell can include one anode, or a pluralityof anodes. The electrochemical cell can include no conductive connector,one conductive connector, or a plurality of conductive connectors. Theelectrochemical cell can include a plurality of conductive connectors,wherein each conductive connector independently electrically connectsthe anode and cathode (e.g., in a parallel, rather than a seriesconfiguration). The plurality of conductive connectors can beapproximately evenly distributed around a perimeter of theelectrochemical cell. The conductive connector can include a connectoror fastener, such as a screw, a bolt, a nut, a washer, or a combinationthereof.

The electrochemical cell can be of any suitable size or configurationsuch that the surface area of the electrochemical cell(s) per unitvolume of water containing phosphorus to be removed is sufficient toeffect removal of the phosphorus during the residence time of the waterin the container. The electrochemical cell can have any suitable totalsurface area per electrochemical cell, or total anode surface areaexposed to water per cell, such as about 1 cm² to about 1,000,000 cm²,about 5 cm² to about 200,000 cm², about 10 cm² to about 50,000 cm²,about 20 cm² to about 40,000 cm², or about 1 cm² or less, or less than,equal to, or greater than 2 cm², 4, 6, 8, 10, 15, 20, 25, 30, 35, 40,45, 50, 75, 100, 150, 200, 250, 500, 750, 1,000, 1,500, 2,000, 2,500,5,000, 7,500, 10,000, 15,000, 20,000, 25,000, 30,000, 35,000, 40,000,45,000, 50,000, 75,000, 100,000, 150,000, 200,000, 500,000, 750,000, orabout 1,000,000 cm² or more. The electrochemical cell can have anysuitable ratio of anode surface area to cathode surface area, such as aratio of anode surface area exposed to water to cathode surface areaexposed to water, such as about 0.1 to about 10, 0.5 to 2, or less than,equal to, or greater than about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8,0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3,2.4, 2.5, 2.6, 2.8, 3, 3.5, 4, 4.5, 5, 5.5, 6, 7, 8, 9, or about 10more. In some embodiments, the anode, the cathode, or a combinationthereof, includes a roughened or etched surface for enhanced surfacearea. For the methods described herein, any suitable number ofelectrochemical cells can be used, such as 1, 1 to 1,000,000, 1 to1,000, 1 to 20, or less than, equal to, or greater than 2, 3, 4, 5, 6,7, 8, 9, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90,100, 125, 150, 175, 200, 225, 250, 300, 400, 500, 750, 1,000, 1,250,1,500, 1,750, 2,000, 2,500, 3,000, 4,000, 5,000, 10,000, 20,000, 50,000,100,000, 250,000, 500,000, or about 1,000,000 or more. The cells can beused in series or parallel electrical arrangement.

The electrochemical cell can include a spacing between a surface of theanode and a surface of the cathode (e.g., between the cathode and atleast about 50% to 100% of the surface area of the anode, or about 80%to about 100%, or less than, equal to, or greater than about 50%, 55,60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, or about 99% or more) ofabout 1 mm to about 110 mm, or about 2 mm to about 30 mm, or less than,equal to, or greater than about 1 mm, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,30, 32, 34, 36, 38, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100,105, or about 110 mm or more.

The electrochemical cell can be planar in form, having a thickness thatis less than a height and width. The electrochemical cell can include aplanar frame of the electrochemical cell and a cathode material includedwithin a perimeter of the frame, wherein the cathode material iselectrically connected to the frame (e.g., via direct contact thereto).The frame can be a structural component of the electrochemical cell. Theframe can be structurally sufficient to maintain its shape in theabsence of any of or all of the anodes. The planar frame and the cathodematerial included within the perimeter of the frame can both be thecathode.

The planar frame can be a nonporous solid material. The planar frame canbe one or more strips of cathode material assembled to form the frame.The planar frame can have a polygonal perimeter, such as a square orrectangle. The cathode material included within the perimeter of theplanar frame can include a porous cathode material, such as includingwire, mesh, screen, a sheet including one or more through-holes, or acombination thereof. The porous cathode material can include a wire meshor a wire screen including the porous cathode material. The porouscathode material included within the perimeter of the planar frame canhave edges that are sandwiched between two of the planar frames, the twoplanar frames held together to secure the porous cathode materialtherebetween with one or more of the conductive connectors, such as viacompression, via conductive connectors passing through one or morethrough-holes of the porous cathode material, or a combination thereof.

The electrochemical cell can include a plurality of pairs of the planarframes (e.g., 2 pairs to 20 pairs, or 2 pairs to 10 pairs, or less than,equal to, or greater than 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,15, 16, 17, 18, 19, or 20 or more pairs), with each pair held togetherto secure the porous cathode material therebetween with one or more ofthe conductive connectors, and each pair separated by one or more of theanodes spanning across the porous cathode material included within theperimeter of the planar frame. The one or more anodes that separate eachpair of planar frames from one another can directly contact a face ofeach pair of planar frames separated therewith. The one or more anodesthat separate each pair of planar frames from one another can directlycontact a face of one of each pair of planar frames separated therewithand can be free of direct contact with a face of the other of each pairof planar frames separated therewith.

The anode can be a strip fastened to the planar frame at two edges ofthe planar frame, wherein the anode is fastened to the planar frame withat least one of the conductive connectors at each of the two edges ofthe planar frame, such that the anode spans across the cathode materialincluded within the perimeter of the planar frame forming a gap betweenthe cathode material included within the perimeter of the planar frameand the anode strip. The anode and the cathode can directly contact oneanother at each of the edges of the planar frame where the anode isfastened to the planar frame via the at least one conductive connector.

The electrochemical cell can include a plurality of the anodes, whereineach anode is a strip fastened to the planar frame at two edges of theplanar frame on a face of the frame, wherein each of the anodes isfastened to the planar frame with at least one of the conductiveconnectors at each of the two edges of the planar frame, such that eachof the anodes spans across the cathode material included within theperimeter of the planar frame forming a gap between the cathode materialincluded within the perimeter of the planar frame and the anode strip,wherein the plurality of the anodes are spaced-apart across the face ofthe such that they do not physically contact one another. Each of theanodes can span across the cathode material included within theperimeter of the planar frame approximately parallel to one another onthe face; anodes on another face of the planar frame can be parallel orperpendicular to the anodes on the first face. The two edges of theplanar frame to which are fastened each anode can be opposite edges ofthe planar frame. The electrochemical cell can have all of its anodes ona single major face of the planar frame, or some of the anodes can be onone major face of the planar frame and the other anodes are on anothermajor face of the frame.

FIG. 1A illustrates an electrochemical cell 110 viewed from a majorface, according to various embodiments. The electrochemical cell 110includes the cathode, wherein the cathode includes a planar frame 120 ofthe electrochemical cell having a polygonal perimeter and a porousmaterial 130 included within the perimeter of the frame that is a wiremesh or a wire screen that is in direct contact with the frame. Theelectrochemical cell 110 includes a plurality of the anodes 140, whereineach anode is a strip fastened to the planar frame at two opposite edgesof the planar frame on a face of the planar frame. Each of the anodes isfastened to the planar frame with at least one of the conductiveconnectors 150 at each of the two edges of the planar frame, such thateach of the anodes are approximately parallel to one another and spanacross the porous material included within the perimeter of the planarframe forming a gap (not shown) between the porous material includedwithin the perimeter of the planar frame and the anode strip. Each anodedirectly contacts the cathode frame at each of the edges of the planarframe where the anode is fastened to the planar frame via the at leastone conductive connector. Conductive connectors (not shown) can also beused that only pass through the planar frame 120 to secure the porousmaterial 130 therebetween. The plurality of the anodes are spaced-apartacross the face of the such that they do not physically contact oneanother, and wherein the gap (not shown) is about 1 mm to about 110 mm.

FIG. 1B illustrates a zoomed-in cutaway edge-view of electrochemicalcell 110, viewed along the perspective shown to the right of FIG. 1A.The electrochemical cell can include a plurality of pairs of the planarframes 120, with each pair held together to secure the porous cathodematerial 130 therebetween with one or more of the conductive connectors(not shown). Anodes 140 spanning across the porous cathode material 130included within the perimeter of the planar frame 120. Each pair ofplanar frames 120 is separated by anodes 140 (only one such anode isshown in FIG. 1). The one or more anodes 140 that separate each pair ofplanar frames from one another directly contact a face of each pair ofplanar frames 120 separated therewith.

Method of Making Struvite.

In various embodiments, the present invention provides a method ofmaking struvite (e.g., NH₄MgPO₄.6H₂O) using the electrochemical cell andmethods of using the same described herein. The method can includeimmersing an electrochemical cell in water including phosphorus having apH of about 10 to about 11 to form treated water including a salt thatincludes the phosphorus. The salt that includes the phosphorus caninclude struvite. The struvite can include the phosphorus from the waterand Mg from the anode. The electrochemical cell can include an anodeincluding Mg, wherein the anode is about 90 wt % to about 100 wt % Mg.The electrochemical cell can include a cathode including Cu, wherein thecathode is about 90 wt % to about 100 wt % Cu. The method can includeseparating the salt including the phosphorus from the treated water toobtain separated struvite and to form separated water having a lowerphosphorus concentration than the water including phosphorus.

The salt that includes the phosphorus can include struvite if sufficientammonia or ammonium ions are available in the water to satisfy thestoichiometric requirements to form struvite. In various embodiments,struvite can be produced when ammonia or ammonium ions are not presentin the source of the water including the phosphorus, or are present onlyin low concentration, such as due to formation of ammonia or ammoniumions by the process of reduction of nitrogen-containing compounds (e.g.,nitrate or nitrite) on the cathode surface of the electrochemical cell.

The electrochemical cell can also include a conductive connector thatelectrically connects the anode and the cathode, the conductiveconnector including Cu, Zn, Fe, Cd, Ni, Sn, Pb, or a combinationthereof. In some embodiments, the anode and the cathode directly contactone another and the electrochemical cell is free of the conductiveconnector.

The method can include purifying the separated struvite, such as byrecrystallization (e.g., dissolution of the solid to form a motherliquor followed by crystallization, leaving behind at least some of theimpurities in the mother liquor), liquid extraction, filtration, or acombination thereof.

The water the includes the phosphorus can further include nitrogen. Thenitrogen can be from any suitable source. The nitrogen can be nativelypresent in the water including the phosphorus, the nitrogen can be addedto the water, or a combination thereof. Adding nitrogen to the waterincluding phosphorus can including adding nitrogen in any suitable form.For example, nitrogen can be added to the water including phosphorus byadding KNO₃, HNO₃, an organic nitrogen compound, or a combinationthereof.

The method can include adding phosphorus to water to form the waterincluding phosphorus. Any suitable phosphorus-containing material can beadded to the water to form the water including phosphorus, such asphosphoric acid, an organic phosphorus-containing material, or acombination thereof.

Method of Making AlPO₄, Aluminum Hydroxide, or a Combination Thereof.

In various embodiments, the present invention provides a method ofmaking AlPO₄, aluminum hydroxide, or a combination thereof, usingembodiments of the electrochemical cell and methods of using the samedescribed herein. The method can include immersing an electrochemicalcell in water including phosphorus having a pH of about 5 to about 7 toform treated water including a salt that includes the phosphorus. Thesalt that includes the phosphorus can include AlPO₄ or a hydratethereof, the AlPO₄ including the phosphorus and Al from the anode;aluminum hydroxide or a hydrate thereof, the aluminum hydroxideincluding Al from the anode; or a combination thereof. Theelectrochemical cell can include an anode including Al, wherein theanode is about 90 wt % to about 100 wt % Al. The electrochemical cellcan include a cathode including Cu, wherein the cathode is about 90 wt %to about 100 wt % Cu. The method can also include separating the saltincluding the phosphorus from the treated water, to form separated waterhaving a lower phosphorus concentration than the water includingphosphorus.

The electrochemical cell can also include a conductive connector thatelectrically connects the anode and the cathode, the conductiveconnector including Cu, Zn, Fe, Cd, Ni, Sn, Pb, or a combinationthereof. In some embodiments, the anode and the cathode directly contactone another and the electrochemical cell is free of the conductiveconnector.

The method can include adding phosphorus to water to form the waterincluding phosphorus. Any suitable phosphorus-containing material can beadded to the water to form the water including phosphorus, such asphosphoric acid, an organic phosphorus-containing material, or acombination thereof.

The method can include purifying the salt including the phosphorus, toprovide purified AlPO₄, purified aluminum hydroxide, or a purifiedmixture of AlPO₄ and aluminum hydroxide. Purification can be performedin any suitable way, such as by recrystallization (e.g., dissolution ofthe solid to form a mother liquor followed by crystallization, leavingbehind at least some of the impurities in the mother liquor), liquidextraction, filtration, or a combination thereof.

Method of Making Magnesium Phosphate, Mg(OH)₂, or a Combination Thereof.

In various embodiments, the present invention provides a method ofmaking magnesium phosphate, Mg(OH)₂, or a combination thereof, usingembodiments of the electrochemical cell and methods of using the samedescribed herein. The method of making magnesium phosphate, Mg(OH)₂, ora combination thereof, can include immersing an electrochemical cell inwater including phosphorus having a pH of about 10 to about 11 to formtreated water including a salt that includes the phosphorus. The saltthat includes the phosphorus can include magnesium phosphate, magnesiumpotassium phosphate, a hydrate thereof, or a combination thereof,Mg(OH)₂ including Mg from the anode; or a combination thereof. Theelectrochemical cell can include an anode including Mg, wherein theanode is about 90 wt % to about 100 wt % Mg. The electrochemical cellcan include a cathode including Cu, wherein the cathode is about 90 wt %to about 100 wt % Cu. The method can also include separating the saltincluding the phosphorus from the treated water, to form separated waterhaving a lower phosphorus concentration than the water includingphosphorus.

The electrochemical cell can also include a conductive connector thatelectrically connects the anode and the cathode, the conductiveconnector including Cu, Zn, Fe, Cd, Ni, Sn, Pb, or a combinationthereof. In some embodiments, the anode and the cathode directly contactone another and the electrochemical cell is free of the conductiveconnector.

The method can include adding phosphorus to water to form the waterincluding phosphorus. Any suitable phosphorus-containing material can beadded to the water to form the water including phosphorus, such asphosphoric acid, an organic phosphorus-containing material, or acombination thereof.

The method can include purifying the salt including the phosphorus, toprovide purified magnesium phosphate, purified Mg(OH)₂, or a purifiedmixture of magnesium phosphate and Mg(OH)₂. Purification can beperformed in any suitable way, such as by recrystallization (e.g.,dissolution of the solid to form a mother liquor followed bycrystallization, leaving behind at least some of the impurities in themother liquor), liquid extraction, filtration, or a combination thereof.

Method of Removing One or More Dissolved Transition Metals,Post-Transition Metals, or Metalloids from Water.

In various embodiments, the present invention provides a method ofremoving one or more dissolved transition metals, post-transitionmetals, or metalloids from water, using an embodiment of theelectrochemical cell and methods of using the same described herein. Thewater can include any suitable amount of phosphorus, or the water can besubstantially free of phosphorus. Any suitable embodiment of theelectrochemical cell or method of using the same described herein in thecontent of removing phosphorus from water can be included in the methodof removing one or more dissolved transition metals, post-transitionmetals, or metalloids from water. The method can include immersing anelectrochemical cell in water including the one or more dissolvedtransition metals, post-transition metals, or metalloids to form treatedwater including a hydroxide salt that includes the one or moretransition metals, post-transition metals, or metalloids. Theelectrochemical cell can include an anode including Mg, Al, Fe, Zn, or acombination thereof. The electrochemical cell can include a cathodeincluding Cu, Ni, Fe, or a combination thereof. The method can includeseparating the salt including the hydroxide salt that includes the oneor more transition metals, post-transition metals, or metalloids, toform separated water having a lower concentration of the one or moretransition metals, post-transition metals, or metalloids than the waterincluding the one or more transition metals, post-transition metals, ormetalloids.

The electrochemical cell can also include a conductive connector thatelectrically connects the anode and the cathode, the conductiveconnector including Cu, Zn, Fe, Cd, Ni, Sn, Pb, or a combinationthereof. In some embodiments, the anode and the cathode directly contactone another and the electrochemical cell is free of the conductiveconnector.

The one or more transition metals, post-transition metals, or metalloidscan be any suitable transition metals, post-transition metals, ormetalloids that can be removed using the electrochemical cell. The oneor more transition metals, post-transition metals, or metalloids caninclude Sc, Y, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Tc, Ru, Rh,Pd, Ag, Hf, Ta, W, Re, Os, Ir, Pt, Au, Rf, Db, Sg, Bh, Hs, Al, Zn, Ga,Cd, In, Sn, Hg, Tl, Pb, Bi, Po, Cn, B, Si, Ge, As, Sb, Te, At, or acombination thereof. The one or more transition metals, post-transitionmetals, or metalloids can include Hg, Fe, Cr, Ni, Zn, Cd, As, or acombination thereof.

The method can remove any suitable amount of the transition metal,post-transition metal, metalloid, or combination thereof from the water.The separated water can have a concentration of the transition metal,post-transition metal, metalloid, or combination thereof, that is about0% to about 70% of a concentration of the transition metal,post-transition metal, metalloid, or combination thereof, in the waterincluding the one or more dissolved transition metals, post-transitionmetals, or metalloids, or about 0% to about 20%, or about 0%, or about1% or less, or less than, equal to, or greater than about 2%, 3, 4, 5,6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 24, 26, 28,30, 35, 40, 45, 50, 55, 60, 65, or about 70% or more of a concentrationof the transition metal, post-transition metal, metalloid, orcombination thereof, in the water including the one or more dissolvedtransition metals, post-transition metals, or metalloids.

EXAMPLES

Various embodiments of the present invention can be better understood byreference to the following Examples which are offered by way ofillustration. The present invention is not limited to the Examples givenherein.

Galvanic cells of several sizes were utilized to evaluate aspects of theprocess as outlined in the Examples. The galvanic cells are referencedas “small”, “medium”, and “large”, as defined below. Magnesium anodeswere AZ91, with 90 wt % Mg, 9 wt % Al, and 1 wt % Zn, and were 99.9 wt %pure. Aluminum anodes were 99.9 wt % pure aluminum. The copper used incopper frames and copper mesh was 99.9 wt % pure copper.

For a small-sized cell, having copper cathodes and either an aluminum ormagnesium anode, the finished size was 5 cm×20 cm with a thickness ofabout 4 mm and utilized copper meshes and an anode having a thickness ofabout 1 mm each. The small-sized cell included a single pair of coppermeshes with an anode sandwiched therebetween, with the copper meshes andthe anode separated from the copper meshes by 0.5 cm using electricallyinsulating plastic screws. The copper meshes were electrically connectedto one another via a copper wire. The anode and the cathode were notelectrically connected to one another (other than via multimeter and thesurrounding water). The resulting surface area of sacrificial anodeexposed to the water was about 400 mm² per cell. FIG. 2A illustrates aphotograph along the edge of an Al—Cu electrochemical cell

For a medium-sized cell, having a copper cathode and either aluminum ormagnesium anodes, the finished size was about 300 mm×45 mm with athickness of about 10 mm and utilized a single pair of copper mesheswith an anode sandwiched therebetween. The copper mesh directlycontacted the anode, and was connected thereto via brass bolts (commonbrass, 67 wt % copper and 33 wt % Zn). The resulting surface area ofsacrificial anode exposed to the water was about 31,400 mm² per cell.FIG. 2B illustrates a photograph along an edge of a plurality ofmedium-sized Al—Cu electrochemical cells.

The large-sized electrochemical cells used in the Examples includedcathodes that are pairs of planar solid copper frames that sandwich acopper mesh, with brass connectors securing the copper frames togetherto secure the copper mesh between the frames. The solid copper framesformed a rigid structural perimeter of the cell, with the copper meshfilling the entire area within the perimeter of each pair of copperframes. A plurality of anode strips, which were magnesium alloy oraluminum, were fastened to the perimeter of the frame with brassfasteners such that they spanned from one edge of the frame to the otherframe, directly contacting the frame and forming a gap between theanodes and the copper mesh. Each electrochemical cell included two pairsof the copper frames having the copper mesh therebetween (i.e., fourcopper frames total, with two copper meshes). A first pair of copperframes had anodes affixed to a single major face thereof, the secondpair of copper frames had anodes affixed to both major faces thereof,with the two pairs of copper frames affixed to one another with brassfasteners such that they do not directly contact one another and suchthat they sandwich the anodes affixed to one major face of the secondpair of copper frames. The brass fasteners were common brass and were 67wt % copper and 33 wt % Zn. The anodes ran horizontally across eachmajor face of the copper frames and parallel to one another, with 6anodes affixed to each face. From one major face of the electrochemicalcell to the other, the order of components is 1) the anodes affixed to amajor face of the first pair of copper frames, 2) the first pair ofcopper frames having copper mesh therebetween, 3) the anodes affixed toa major face of the second pair of copper frames, 4) the second pair ofcopper frames having copper mesh therebetween, and 5) the anodes affixedto the other major face of the second pair of copper frames. The ratioof anode surface area to cathode surface area for the electrochemicalcell was about 1:1.

For a large-sized cell, each copper frame had a thickness of 3.175 mm (⅛inch). The height of the copper frame was 400 mm and the length of thecopper frame was 400 mm. The copper mesh had a thickness of 1.5875 mm,such that each pair of copper frames sandwiching the copper mesh had athickness of about 8 mm. The anode strips had a length of 400 mm, awidth of 45 mm, and a thickness of 6 mm. The thickness of the entireelectrochemical cell was about 30 mm. The gap between the anodes on eachface of the copper frames was 12-18 mm. The gap between the anodesaffixed to each pair of copper frames and the copper mesh sandwichedtherebetween was 12-18 mm. The large-sized cell using aluminum anodesincluded an anode surface area exposed to the water of about 290,000mm², and the large-sized cell using magnesium included an anode surfacearea exposed to the water of about 868,000 mm².

FIG. 2C illustrates a photograph of a major face of the large-sizedMg—Cu electrochemical cell used in the Examples. FIGS. 2D and 2Eillustrate close-up photographs of an edge of the large-sized Mg—Cuelectrochemical cell used in the Examples.

In the Examples herein, the Al—Cu or Mg—Cu electrochemical cell wascompletely immersed in water in a container, such that electrochemicalcell was vertically oriented with the anodes running vertically. Whenmultiple electrochemical cells were used, they were separated by about25 mm using a wooden frame. In the middle of the container a mechanicalstirrer was used to agitate the water therein. Water was filtered andfed into the container using a pump. Another pump was used to circulatewater and filter water within the container (e.g., to remove precipitatetherefrom), with water pumped from one side of the container andrecirculated to the other side. A pump connected to a reservoir of 10%HCl was used to add HCl to the container to adjust the pH of the watertherein. The water in the container was measured to determine the pHthereof, which was used to determine the amount of acid that needed tobe added from the reservoir to maintain a specific pH. The water fedinto the container was analyzed to determine initial pH, initialconductivity, and initial reactive phosphorus content. For the Mg—Cucell, the water fed into the container was also analyzed to determinethe initial dissolved magnesium content. The pH and conductivity ofwater in the container was measured. The container included a drain atthe water level of the container to allow water to exit the system. Thewater that exited the system was analyzed to determine the final pH,final conductivity, and final reactive phosphorus content. For the Al—Cucell, the water exiting the containing was analyzed to determine thetotal Al and dissolved Al. For the Mg—Cu cell, the water exiting thecontainer was analyzed to determine the dissolved magnesium content.FIG. 2F illustrates a photograph showing a top-view of the system usedin the Examples, with the specific embodiment shown in the photographhaving 12 electrochemical cells (6 in front, and 6 in back arrangededge-to-edge with the 6 in front). FIG. 2G illustrates a photographshowing a side-view of the system used in the Examples, with thespecific embodiment having 12 electrochemical cells therein.

The “reactive phosphorus concentration” refers to the soluble reactivephosphorus in solution (e.g., orthophosphate) and was measured by US-EPA365.1: Determination of Phosphorus by Semi-Automated Colorimetry. The pHwas measured using an Oakton® pH 700 meter. The conductivity wasmeasured using an Oakton® CON 150 meter. The dissolved magnesium contentwas measured using a Thermo Scientific™ Dionex™ Aquion™ ionchromatography system. The total aluminum content and dissolved aluminumcontent were measured using a Hach Aluminum TNT Plus™ vial test.Dissolved Al was determined at the pH of the water exiting thecontainer. Total Al was determined by adjusting the pH to 2.

Example 1. Removal of Phosphorus with Al—Cu Cell, Initial PConcentration 0.033 ppm

Water was taken from one of the channels of a local lake and theresidence time in the galvanic process was modified by adjusting thewater flow to provide specific residence times while keeping the othervariables of the system constant (pH, conductivity, and concentration ofphosphorus). Residence time (i.e., volume of the container divided bythe flow rate) was gradually decreased until removal performance wasreduced and then held constant for this Example. For a low initialconcentration of phosphorus (0.033 ppm) residence time was reduced toapproximately 15 min while maintaining an average of about 90% removalof phosphorus. The Al—Cu cell was medium-sized. The results are shown inTable 1.

TABLE 1 Removal of phosphorus with Al-Cu cell, initial P concentration0.033 ppm. Water Source Local Lake (C44) Flow Rate (mL/min) 650 950 1261Residence Time (mins) 30 20 15 Electrochemical cells 8 8 8 Initial pH8.43 8.43 8.43 Final pH 7.05 7.03 7.02 Initial Conductivity (μS) 776 776776 Final Conductivity (μS) 778 778 778 Initial reactive-P (ppm) 0.0330.033 0.033 Final reactive-P (ppm) 0.0028 0.0028 0.0027 % P removal 91.591.5 91.5 Final total Al (ppm) 1.18 1.00 1.00 Final dissolved Al (ppm)0.134 0.115 0.110

Example 2. Removal of Phosphorus with Al—Cu Cell, Initial PConcentration 0.451 ppm

Water from a local inland wastewater treatment facility was processed toevaluate the effect of increasing solution conductivity. Residence timewas held constant during this Example at 21 min. Conductivity wasmodified by adding NaCl. This Example demonstrates the beneficial effectof increased conductivity on the effectiveness of phosphorus removal.The Al—Cu cell was medium-sized. The results are shown in Table 2.

TABLE 2 Removal of phosphorus with Al-Cu cell, initial P concentration0.451 ppm. Cell size = medium. Water Source Inland Wastewater Plant FlowRate (mL/min) 920 920 Residence Time (mins) 21 21 Electrochemical cells8 8 Initial pH 7.69 7.69 Final pH 7.02 6.93 Initial Conductivity (μS)673 960 Final Conductivity (μS) 672 962 Initial reactive-P (ppm) 0.4510.451 Final reactive-P (ppm) 0.062 0.027 % P removal 86.3 94.0 Finaltotal Al (ppm) 1.15 1.81 Final dissolved Al (ppm) 0.037 0.056

Example 3. Removal of Phosphorus with Al—Cu Cell, Initial PConcentration 0.392 ppm

A coastal wastewater treatment plant effluent with high electricalconductivity was treated using the medium Al—Cu cell. As noted inExample 2 above, increased conductivity is beneficial. The water treatedin this Example was from a coastal location where the salt (NaCl)concentration results in elevated conductivity. The purpose of thisExample is to evaluate the loss of sacrificial electrode material to thetreated water solution and to evaluate this relationship as a functionof pH. The final phosphorus removal efficiency remained constant;however, the concentration of total aluminum (dissolved and solid)decreases when modifying the pH from pH 7 to pH 6.5. This Exampledemonstrates the ability to control the loss of material from thesacrificial electrode by adjusting the pH. The results are shown inTable 3.

TABLE 3 Removal of phosphorus with Al-Cu cell, initial P concentration0.392 ppm. Cell size = medium. Water Source Coastal Wastewater FacilityFlow Rate (mL/min) 920 920 Residence Time (mins) 21 21 Electrochemicalcells 8 8 Initial pH 9.06 9.06 Final pH 7.00 6.47 Initial Conductivity(μS) 3100 3100 Final Conductivity (μS) 3141 3110 Initial reactive-P(ppm) 0.392 0.392 Final reactive-P (ppm) 0.042 0.032 % P removal 89.391.8 Final total Al (ppm) 2.24 1.90 Final dissolved Al (ppm) 0.055 0.059

Example 4. Removal of Phosphorus with Al—Cu Cell, Initial PConcentration 0.648-0.762 ppm

Water from a local fresh water retention pond was spiked with phosphoricacid to obtain a concentration of 0.75 ppm of phosphorus and was treatedutilizing multiple galvanic cells in a continuous flow apparatus with aflow of about 2 gallons per minute (GPM) (large cell). The pH of thewater was adjusted incrementally downward to values between 7 and 6. Anincrease the percentage of removal from 82% at pH=7 to 97% at pH=6 wasobserved, while reducing the soluble aluminum remaining in the treatedwater. The results are shown in Table 4.

TABLE 4 Removal of phosphorus with Al-Cu cell, initial P concentration0.648-0.762 ppm. Cell size = large. Water Source Retention Pond FlowRate (mL/min) 7797.1 7797.1 7797.1 Residence Time (mins) 20-25 20-2520-25 Electrochemical cells 12 12 12 Initial pH 7.03 7.06 7.03 Final pH6.96 6.5 5.95 Initial Conductivity (μS) 680.9 689 680.9 FinalConductivity (μS) 671.7 676.3 695.4 Initial reactive-P (ppm) 0.742 0.6480.762 Final reactive-P (ppm) 0.135 0.047 0.024 % P removal 81.8 92.796.9 Final total Al (ppm) 3.17 2.78 4.38 Final dissolved Al (ppm) 0.0350.029 0.028

Example 5. Conductivity Effects on Electrical Current Generated by Al—CuCell Versus Time

Using a small-sized cell, Al-foil and Cu screens having a size of 5 cm×2cm were separated by 0.5 cm using plastic screws. The Al-foil/Cu wasplaced in a simple compartment with magnetic stirring that was filledwith 30 mL water from a local freshwater retention pond. The currentswere measured with a Keithley 175 multimeter connected in series. Theinitial conductivity was adjusted with NaCl. The electrical currentgenerated by the Al—Cu galvanic pair in the Al—Cu cell was measured.This electric current is a measure of the amount of the anode materialthat was transformed in the electrodes as a function of time, e.g., theoxidation reaction of aluminum to generate aluminum ions and thedecomposition of water on the copper electrode to generate hydrogen andhydroxyl ions.

FIG. 3 shows the variation of the electric current that was generated bythe Al—Cu galvanic pair as a function of the conductivity of thesolution. The initial pH of the water was not modified and was about 7.An increase of the initial conductivity of the solution up to a value of1000 μS increases the electric current due to a decrease in theresistance between the electrodes thereby increasing the rate of thechemical reactions at the electrode surface. A similar result wasobtained in Example 2. Increasing the conductivity to values higher than1000 μS resulted in little change in the electrical current because athigher conductivity values the rate limiting step of the reaction is thekinetics of the chemical processes at the surface of the electrodes.

Example 6. pH Effects on Electrical Current Generated by Al—Cu CellVersus Time

The same experimental conditions as Example 5 were used, but adjustingthe initial pH with NaOH, with the initial conductivity of the wateradjusted with NaCl to about 1000 μS. FIG. 4 shows the variation of theelectric current generated by the Al—Cu galvanic pair as a function ofthe pH of the solution. Decreasing the pH of the solution favors thekinetics of the decomposition of water on the copper electrode, whichtranslates into an increase in electrical current by the Al—Cu galvanicpair.

Example 7. Conductivity Effects on Electrical Current Generated by Mg—CuCell Versus Time

The same experimental conditions as Example 5 were used, withoutmodification of pH, and with modification of conductivity using NaCl.FIG. 5A shows the variation of the electric current that circulates inthe Galvanic pair of Mg—Cu as a function of the water conductivity of alocal freshwater holding pond. The increase of the conductivity of thewater produces remarkable increases in the electric current of theelectrochemical cell. The effect of this increase in conductivity in thekinetics of chemical reactions is shown in FIG. 5B, where it improvesthe kinetics of the pH increase.

Example 8. Mg—Cu Cell, Initial P Concentration 0.392-0.451

Two bodies of water from treatment plants were compared; the watercollected from a coastal waste-water treatment plant (WWTP) has threetimes more conductivity than the water from an inland WWTP due to saltwater inclusion in the processing system. The higher conductivity favorsthe reaction kinetics and thus for the same residence time a greaterphosphorus removal occurs in the higher conductivity water whileconsuming the same amount of sacrificial anode (resulting in the sameamount of magnesium ions in solution) as with the lower conductivity.The Mg—Cu cell was medium-sized. The results are shown in Table 5.

TABLE 5 Mg-Cu cell, initial P concentration 0.392-0.451. Cell size =medium. Inland WWTP Coastal WWTP Flow Rate (mL/min) 370 370 ResidenceTime (mins) 50 50 Electrodes 8 8 Initial pH 7.69 9.06 Final pH 10.9010.94 Initial Conductivity (uS) 960 3100 Final Conductivity (uS) 11243148 Initial reactive-P (ppm) 0.451 0.392 Final reactive-P (ppm) 0.1220.061 % P removal 72.9 84.4 Initial dissolved Magnesium (ppm) 17 56Final dissolved Magnesium (ppm) 44 95

The terms and expressions that have been employed are used as terms ofdescription and not of limitation, and there is no intention in the useof such terms and expressions of excluding any equivalents of thefeatures shown and described or portions thereof, but it is recognizedthat various modifications are possible within the scope of theembodiments of the present invention. Thus, it should be understood thatalthough the present invention has been specifically disclosed byspecific embodiments and optional features, modification and variationof the concepts herein disclosed may be resorted to by those of ordinaryskill in the art, and that such modifications and variations areconsidered to be within the scope of embodiments of the presentinvention.

Exemplary Embodiments

The following exemplary embodiments are provided, the numbering of whichis not to be construed as designating levels of importance:

Embodiment 1 provides a method of removing phosphorus from water, themethod comprising:

immersing an electrochemical cell in water comprising phosphorus to formtreated water comprising a salt that comprises the phosphorus, theelectrochemical cell comprising

-   -   an anode comprising Mg, Al, Fe, Zn, or a combination thereof,    -   a cathode having a different composition than the anode, the        cathode comprising Cu, Ni, Fe, or a combination thereof, and

separating the salt comprising the phosphorus from the treated water, toform separated water having a lower phosphorus concentration than thewater comprising phosphorus.

Embodiment 2 provides the method of Embodiment 1, wherein the anode andthe cathode directly contact one another.

Embodiment 3 provides the method of any one of Embodiments 1-2, whereinthe electrochemical cell further comprises a conductive connector thatelectrically connects the anode and the cathode, the conductiveconnector comprising Cu, Zn, Fe, Cd, Ni, Sn, Pb, or a combinationthereof.

Embodiment 4 provides the method of any one of Embodiments 1-3, whereinthe electrochemical cell is a galvanic cell.

Embodiment 5 provides the method of any one of Embodiments 1-4, whereinno electrical potential is applied across the anode and the cathode ofthe electrochemical cell.

Embodiment 6 provides the method of any one of Embodiments 1-5, whereinthe electrochemical cell is an electrolytic cell.

Embodiment 7 provides the method of any one of Embodiments 1-6,comprising applying an electrical potential across the anode and thecathode of the electrochemical cell.

Embodiment 8 provides the method of any one of Embodiments 1-7,comprising applying an electrical potential across the anode and thecathode that is greater than the galvanic corrosion potential of theelectrochemical cell.

Embodiment 9 provides the method of any one of Embodiments 1-8,comprising applying an electrical potential across the anode and thecathode that is less than the galvanic corrosion potential of theelectrochemical cell.

Embodiment 10 provides the method of any one of Embodiments 1-9, whereinan electrical potential across the anode and the cathode is equal to thegalvanic corrosion potential of the electrochemical cell.

Embodiment 11 provides the method of any one of Embodiments 1-10,wherein the immersing of the electrochemical cell in the watercomprising phosphorus comprises partial immersion.

Embodiment 12 provides the method of any one of Embodiments 1-11,wherein the immersing of the electrochemical cell in the watercomprising phosphorus comprises complete immersion.

Embodiment 13 provides the method of any one of Embodiments 1-12,wherein the phosphorus in the water comprising the phosphorus is in theform of elemental phosphorus, inorganic phosphorus, organic phosphorus,a dissolved form of phosphorus, a solid form of phosphorus, oxidizedphosphorus, or a combination thereof.

Embodiment 14 provides the method of any one of Embodiments 1-13,wherein the water comprising the phosphorus has a total phosphorusconcentration of about 0.001 ppm to about 10,000 ppm.

Embodiment 15 provides the method of any one of Embodiments 1-14,wherein the water comprising the phosphorus has a total phosphorusconcentration of about 0.01 ppm to about 20 ppm.

Embodiment 16 provides the method of any one of Embodiments 1-15,wherein the separated water has a total phosphorus concentration ofabout 0 ppm to about 1 ppm.

Embodiment 17 provides the method of any one of Embodiments 1-16,wherein the separated water has a total phosphorus concentration ofabout 0.0001 ppm to 0.1 ppm.

Embodiment 18 provides the method of any one of Embodiments 1-17,wherein the separated water has a total phosphorus concentration ofabout 0.0001 ppm to 0.05 ppm.

Embodiment 19 provides the method of any one of Embodiments 1-18,wherein the separated water has a dissolved phosphorus concentration ofabout 0 ppm to about 1 ppm.

Embodiment 20 provides the method of any one of Embodiments 1-19,wherein the separated water has a dissolved phosphorus concentration ofabout 0.0001 ppm to 0.1 ppm.

Embodiment 21 provides the method of any one of Embodiments 1-20,wherein the separated water has a dissolved phosphorus concentration ofabout 0.0001 ppm to 0.05 ppm.

Embodiment 22 provides the method of any one of Embodiments 1-21,wherein the separated water has a total phosphorus concentration that isabout 0% to about 70% of the total phosphorus concentration of the watercomprising phosphorus.

Embodiment 23 provides the method of any one of Embodiments 1-22,wherein the separated water has a total phosphorus concentration that isabout 0% to about 20% of the total phosphorus concentration of the watercomprising phosphorus.

Embodiment 24 provides the method of any one of Embodiments 1-23,wherein the separated water has a dissolved phosphorus concentrationthat is about 0% to about 70% of the dissolved phosphorus concentrationof the water comprising phosphorus.

Embodiment 25 provides the method of any one of Embodiments 1-24,wherein the separated water has a dissolved phosphorus concentrationthat is about 0% to about 20% of the dissolved phosphorus concentrationof the water comprising phosphorus.

Embodiment 26 provides the method of any one of Embodiments 1-25,wherein the water comprising the phosphorus has a reactive phosphorusconcentration of about 0.001 ppm to about 10,000 ppm.

Embodiment 27 provides the method of any one of Embodiments 1-26,wherein the water comprising the phosphorus has a reactive phosphorusconcentration of about 0.01 ppm to about 20 ppm.

Embodiment 28 provides the method of any one of Embodiments 1-27,wherein the separated water has a reactive phosphorus concentration ofabout 0 ppm to about 1 ppm.

Embodiment 29 provides the method of any one of Embodiments 1-28,wherein the separated water has a reactive phosphorus concentration ofabout 0.0001 ppm to 0.1 ppm.

Embodiment 30 provides the method of any one of Embodiments 1-29,wherein the separated water has a reactive phosphorus concentration ofabout 0.0001 ppm to 0.05 ppm.

Embodiment 31 provides the method of any one of Embodiments 1-30,wherein the separated water has a reactive phosphorus concentration thatis about 0% to about 20% of the total phosphorus concentration of thewater comprising phosphorus.

Embodiment 32 provides the method of any one of Embodiments 1-31,wherein the separated water has a reactive phosphorus concentration thatis about 0% to about 70% of the dissolved phosphorus concentration ofthe water comprising phosphorus.

Embodiment 33 provides the method of any one of Embodiments 1-32,wherein during the immersing of the electrochemical cell in the watercomprising phosphorus, the water comprising phosphorus has a pH of about2 to about 14.

Embodiment 34 provides the method of any one of Embodiments 1-33,wherein during the immersing of the electrochemical cell in the watercomprising phosphorus, the water comprising phosphorus has a pH of about5 to about 11.

Embodiment 35 provides the method of any one of Embodiments 1-34,wherein during the immersing of the electrochemical cell in the watercomprising phosphorus, the water comprising phosphorus has a pH of about5 to about 7.

Embodiment 36 provides the method of any one of Embodiments 1-35,wherein during the immersing of the electrochemical cell in the watercomprising phosphorus, the water comprising phosphorus has a pH of about10 to about 11.

Embodiment 37 provides the method of any one of Embodiments 1-36,further comprising adding acid, base, or a combination thereof to thewater comprising phosphorus to adjust the pH thereof.

Embodiment 38 provides the method of Embodiment 37, wherein the acid,base, or combination thereof is added to the water comprising phosphorusbefore the immersing of the electrochemical cell in the water comprisingphosphorus, during the immersing of the electrochemical cell in thewater comprising phosphorus, after the immersing of the electrochemicalcell in the water comprising phosphorus, or a combination thereof.

Embodiment 39 provides the method of any one of Embodiments 1-38,further comprising recirculating the water comprising phosphorusimmersing the electrochemical cell to contact the water comprisingphosphorus with the electrochemical cell multiple times.

Embodiment 40 provides the method of any one of Embodiments 1-39,wherein at least some of the salt comprising the phosphorus in thetreated water comprises a solid.

Embodiment 41 provides the method of any one of Embodiments 1-40,wherein during the immersion of the electrochemical cell in the watercomprising the phosphorus, a solid comprising the phosphorus is formed.

Embodiment 42 provides the method of Embodiment 41, wherein formation ofthe solid comprising the phosphorus comprises precipitation,flocculation, or a combination thereof.

Embodiment 43 provides the method of any one of Embodiments 1-42,wherein separating the salt comprising the phosphorus from the treatedwater comprises decantation, settling, filtration, or a combinationthereof.

Embodiment 44 provides the method of any one of Embodiments 1-43,further comprising separating the treated water from the electrochemicalcell.

Embodiment 45 provides the method of any one of Embodiments 1-44,wherein the anode is a sacrificial anode.

Embodiment 46 provides the method of any one of Embodiments 1-45,wherein the salt comprising the phosphorus comprises a material from theanode.

Embodiment 47 provides the method of any one of Embodiments 1-46,further comprising forming a hydroxide salt comprising a material fromthe anode during the immersing of the electrochemical cell in the watercomprising phosphorus.

Embodiment 48 provides the method of Embodiment 47, wherein theseparating of the salt comprising the phosphorus from the treated waterfurther comprises separating the hydroxide salt comprising the materialfrom the anode from the treated water.

Embodiment 49 provides the method of any one of Embodiments 1-48,wherein the water comprising phosphorus further comprises a dissolvedtransition metal, post-transition metal, metalloid, or a combinationthereof, further comprising forming a hydroxide salt comprising thetransition metal, post-transition metal, or metalloid during theimmersing of the electrochemical cell in the water comprisingphosphorus.

Embodiment 50 provides the method of Embodiment 49, wherein theseparating of the salt comprising the phosphorus from the treated waterfurther comprises separating the hydroxide salt comprising thetransition metal, post-transition metal, or metalloid from the treatedwater.

Embodiment 51 provides the method of any one of Embodiments 49-50,wherein the transition metal, post-transition metal, or metalloid is Sc,Y, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf,Ta, W, Re, Os, Ir, Pt, Au, Rf, Db, Sg, Bh, Hs, Al, Zn, Ga, Cd, In, Sn,Hg, Tl, Pb, Bi, Po, Cn, B, Si, Ge, As, Sb, Te, At, or a combinationthereof.

Embodiment 52 provides the method of any one of Embodiments 49-51,wherein the transition metal, post-transition metal, or metalloid is Hg,Fe, Cr, Ni, Zn, Cd, As, or a combination thereof.

Embodiment 53 provides the method of any one of Embodiments 49-52,wherein the separated water has a concentration of the transition metal,post-transition metal, metalloid, or combination thereof, that is about0% to about 70% of a concentration of the transition metal,post-transition metal, metalloid, or combination thereof, in the watercomprising phosphorus.

Embodiment 54 provides the method of any one of Embodiments 49-53,wherein the separated water has a concentration of the transition metal,post-transition metal, metalloid, or combination thereof, that is about0% to about 20% of a concentration of the transition metal,post-transition metal, metalloid, or combination thereof, in the watercomprising phosphorus.

Embodiment 55 provides the method of any one of Embodiments 1-54,comprising forming H₂ and HO⁻ at the anode during the immersing of theelectrochemical cell in the water comprising phosphorus.

Embodiment 56 provides the method of any one of Embodiments 1-55,comprising forming H₂ and HO⁻ at the cathode during the immersing of theelectrochemical cell in the water comprising phosphorus.

Embodiment 57 provides the method of any one of Embodiments 1-56,comprising forming H₂O₂, HO₂ ⁻, or a combination thereof at the cathodeduring the immersing of the electrochemical cell in the water comprisingphosphorus.

Embodiment 58 provides the method of any one of Embodiments 1-57,further comprising applying shear to the water comprising phosphorusduring the immersing of the electrochemical cell in the water comprisingphosphorus.

Embodiment 59 provides the method of Embodiment 58, wherein the shear issufficient to dislodge at least some bubbles comprising H₂ from thesurface of the anode, cathode, or a combination thereof.

Embodiment 60 provides the method of any one of Embodiments 58-59,wherein the shear is sufficient to at least partially prevent oxideformation at the surface of the anode.

Embodiment 61 provides the method of any one of Embodiments 58-60,wherein the shear is sufficient to at least partially preventagglomeration of the salt comprising the phosphorus on the surface ofthe anode.

Embodiment 62 provides the method of any one of Embodiments 1-61,further comprising applying a mechanical force to the electrochemicalcell sufficient to dislodge at least some bubbles comprising H₂ from thesurface of the anode, cathode, or a combination thereof, at leastpartially prevent oxide formation at the surface of the anode, at leastpartially prevent agglomeration of the salt comprising the phosphorus onthe surface of the anode, or a combination thereof.

Embodiment 63 provides the method of any one of Embodiments 1-62,wherein the water comprising phosphorus further comprises nitrogen.

Embodiment 64 provides the method of Embodiment 63, wherein the nitrogenin the water comprising phosphorus is in the form of elemental nitrogen,inorganic nitrogen, organic nitrogen, a dissolved form of nitrogen, asolid form of nitrogen, oxidized nitrogen, or a combination thereof.

Embodiment 65 provides the method of any one of Embodiments 63-64,wherein the water comprising the phosphorus has a total nitrogenconcentration of about 0.001 ppm to about 20 ppm.

Embodiment 66 provides the method of any one of Embodiments 63-65,wherein the water comprising the phosphorus has a total nitrogenconcentration of about 1 ppm to about 5 ppm.

Embodiment 67 provides the method of any one of Embodiments 63-66,wherein the separated water has a total nitrogen concentration of about0 ppm to about 2 ppm.

Embodiment 68 provides the method of any one of Embodiments 63-67,wherein the separated water has a total nitrogen concentration of about0 ppm to about 1 ppm.

Embodiment 69 provides the method of any one of Embodiments 63-68,wherein the separated water has a dissolved nitrogen concentration ofabout 0 ppm to about 2 ppm.

Embodiment 70 provides the method of any one of Embodiments 63-69,wherein the separated water has a dissolved nitrogen concentration ofabout 0 ppm to about 1 ppm.

Embodiment 71 provides the method of any one of Embodiments 63-70,wherein the separated water has a total nitrogen concentration that isabout 0% to about 70% of a total nitrogen concentration of the watercomprising phosphorus.

Embodiment 72 provides the method of any one of Embodiments 63-71,wherein the separated water has a total nitrogen concentration that isabout 0% to about 30% of a total nitrogen concentration of the watercomprising phosphorus.

Embodiment 73 provides the method of any one of Embodiments 63-72,wherein the separated water has a dissolved nitrogen concentration thatis about 0% to about 70% of a dissolved nitrogen concentration of thewater comprising phosphorus.

Embodiment 74 provides the method of any one of Embodiments 63-73,wherein the separated water has a total nitrogen concentration that isabout 0% to about 30% of a dissolved nitrogen concentration of the watercomprising phosphorus.

Embodiment 75 provides the method of any one of Embodiments 63-74,further comprising forming NH₃, NH₄ ⁺, or a combination thereof, at thecathode, wherein the NH₃ and NH₄ ⁺ comprise the nitrogen from the watercomprising phosphorus.

Embodiment 76 provides the method of any one of Embodiments 63-75,further comprising forming a salt comprising the nitrogen during theimmersing of the electrochemical cell in the water comprisingphosphorus.

Embodiment 77 provides the method of Embodiment 76, wherein theseparating of the salt comprising the phosphorus from the treated waterfurther comprises separating the salt comprising the nitrogen from thetreated water.

Embodiment 78 provides the method of any one of Embodiments 76-77,wherein the salt comprising the nitrogen comprises NH₄MgPO₄ or a hydratethereof.

Embodiment 79 provides the method of any one of Embodiments 1-78,wherein the cathode comprises Cu.

Embodiment 80 provides the method of any one of Embodiments 1-79,wherein the cathode is substantially free of materials other than Cu.

Embodiment 81 provides the method of any one of Embodiments 1-80,wherein the cathode is about 50 wt % to about 100 wt % Cu.

Embodiment 82 provides the method of any one of Embodiments 1-81,wherein the cathode is about 90 wt % to about 100 wt % Cu.

Embodiment 83 provides the method of any one of Embodiments 1-82,wherein the anode comprises an alloy comprising Mg and Al.

Embodiment 84 provides the method of any one of Embodiments 1-83,wherein Mg and Al are about 50 wt % to about 100 wt % of the anode.

Embodiment 85 provides the method of any one of Embodiments 1-84,wherein the anode is substantially free of materials other than Mg, Mgalloys, and Al.

Embodiment 86 provides the method of any one of Embodiments 1-85,wherein the anode further comprises Ag, Pt, Au, or a combinationthereof.

Embodiment 87 provides the method of Embodiment 86, wherein the Ag, Pt,Au, or the combination thereof is about 0.0001 wt % to about 20 wt % ofthe anode.

Embodiment 88 provides the method of any one of Embodiments 86-87,wherein the Ag, Pt, Au, or the combination thereof is about 0.0001 wt %to about 5 wt % of the anode.

Embodiment 89 provides the method of any one of Embodiments 1-88,wherein the anode comprises Mg.

Embodiment 90 provides the method of Embodiment 89, wherein the anode issubstantially free of materials other than Mg or alloys thereof.

Embodiment 91 provides the method of any one of Embodiments 89-90,wherein the anode is about 50 wt % to about 100 wt % Mg or alloysthereof.

Embodiment 92 provides the method of any one of Embodiments 89-91,wherein the anode is about 90 wt % to about 100 wt % Mg or alloysthereof.

Embodiment 93 provides the method of any one of Embodiments 89-92,wherein the cathode comprises Cu.

Embodiment 94 provides the method of any one of Embodiments 89-93,wherein the salt comprising the phosphorus comprises magnesiumphosphate, magnesium potassium phosphate, a hydrate thereof, or acombination thereof, wherein the magnesium phosphate or magnesiumpotassium phosphate comprises Mg from the anode.

Embodiment 95 provides the method of Embodiment 94, wherein theseparating of the salt comprising the phosphorus from the treated waterfurther comprises separating the magnesium phosphate from the treatedwater.

Embodiment 96 provides the method of any one of Embodiments 89-95,wherein the water comprising phosphorus further comprises nitrogen,wherein the salt comprising the phosphorus comprises NH₄MgPO₄ or ahydrate thereof, the NH₄MgPO₄ comprising the phosphorus and Mg from theanode.

Embodiment 97 provides the method of any one of Embodiments 89-96,further comprising forming Mg(OH)₂ comprising Mg from the anode duringthe immersing of the electrochemical cell in the water comprisingphosphorus.

Embodiment 98 provides the method of Embodiment 97, wherein theseparating of the salt comprising the phosphorus from the treated waterfurther comprises separating the Mg(OH)₂ from the treated water.

Embodiment 99 provides the method of any one of Embodiments 89-98,wherein during the immersing of the electrochemical cell in the watercomprising phosphorus, the water comprising phosphorus has a pH of about9.5 to about 11.5.

Embodiment 100 provides the method of any one of Embodiments 89-99,wherein during the immersing of the electrochemical cell in the watercomprising phosphorus, the water comprising phosphorus has a pH of about10 to about 11.

Embodiment 101 provides the method of any one of Embodiments 89-100,further comprising regulating a rate of introduction of fresh watercomprising the phosphorus to the electrochemical cell such that thewater comprising the phosphorus that immerses the electrochemical cellis maintained at a pH of about 10 to about 11.

Embodiment 102 provides the method of any one of Embodiments 89-101,further comprising immersing the electrochemical cell in the watercomprising the phosphorus until the water comprising the phosphorusreaches a pH of about 10 to about 11, and then regulating a rate ofintroduction of fresh water comprising the phosphorus to theelectrochemical cell such that the water comprising the phosphorus thatimmerses the electrochemical cell is maintained at a pH of about 10 toabout 11.

Embodiment 103 provides the method of any one of Embodiments 1-102,wherein the anode comprises Al.

Embodiment 104 provides the method of Embodiment 103, wherein the anodeis substantially free of materials other than Al.

Embodiment 105 provides the method of any one of Embodiments 103-104,wherein the anode is about 50 wt % to about 100 wt % Al.

Embodiment 106 provides the method of any one of Embodiments 103-105,wherein the anode is about 90 wt % to about 100 wt % Al.

Embodiment 107 provides the method of any one of Embodiments 103-106,wherein the cathode comprises Cu.

Embodiment 108 provides the method of any one of Embodiments 103-107,wherein the salt comprising the phosphorus comprises AlPO₄ or a hydratethereof.

Embodiment 109 provides the method of Embodiment 108, wherein theseparating of the salt comprising the phosphorus from the treated waterfurther comprises separating the AlPO₄ from the treated water.

Embodiment 110 provides the method of any one of Embodiments 103-109,further comprising forming aluminum hydroxide or a hydrate thereof, thealuminum hydroxide comprising Al from the anode during the immersing ofthe electrochemical cell in the water comprising phosphorus.

Embodiment 111 provides the method of Embodiment 110, wherein theseparating of the salt comprising the phosphorus from the treated waterfurther comprises separating the aluminum hydroxide from the treatedwater.

Embodiment 112 provides the method of any one of Embodiments 103-111,wherein during the immersing of the electrochemical cell in the watercomprising the phosphorus, the water comprising phosphorus has a pH ofabout 4 to about 8.

Embodiment 113 provides the method of any one of Embodiments 103-112,wherein during the immersing of the electrochemical cell in the watercomprising the phosphorus, the water comprising phosphorus has a pH ofabout 5 to about 7.

Embodiment 114 provides the method of any one of Embodiments 103-113,further comprising regulating a rate of introduction of an acid to thewater comprising the phosphorus such that the water comprising thephosphorus that immerses the electrochemical cell is maintained at a pHof about 5 to about 7.

Embodiment 115 provides the method of Embodiment 114, wherein the acidis added to the water comprising the phosphorus prior to the immersionof the electrochemical cell in the water comprising the phosphorus,during the immersion of the electrochemical cell in the water comprisingthe phosphorus, after the immersion of the electrochemical cell in thewater comprising the phosphorus, or a combination thereof.

Embodiment 116 provides the method of any one of Embodiments 103-115,wherein the acid comprises sulfuric acid, acetic acid, hydrochloricacid, or a combination thereof.

Embodiment 117 provides the method of any one of Embodiments 103-116,comprising flocculating salts comprising Al from the treated water.

Embodiment 118 provides the method of any one of Embodiments 1-117,wherein the cathode has a work function that is larger than a workfunction of the anode.

Embodiment 119 provides the method of any one of Embodiments 3-118,wherein the conductive connector has a work function that is between awork function of the anode and a work function of the cathode.

Embodiment 120 provides the method of any one of Embodiments 3-119,wherein the conductive connector comprises Cu.

Embodiment 121 provides the method of any one of Embodiments 3-120,wherein the conductive connector comprises Zn.

Embodiment 122 provides the method of any one of Embodiments 3-121,wherein the conductive connector comprises an alloy comprising Cu andZn.

Embodiment 123 provides the method of any one of Embodiments 3-122,wherein the conductive connector comprises brass.

Embodiment 124 provides the method of any one of Embodiments 3-123,wherein the conductive connector comprises brass, wherein the conductiveconnector is substantially free of other materials.

Embodiment 125 provides the method of any one of Embodiments 3-124,wherein the electrochemical cell comprises a plurality of the conductiveconnectors, each conductive connector independently electricallyconnecting the anode and cathode.

Embodiment 126 provides the method of Embodiment 125, wherein theplurality of conductive connectors are approximately evenly distributedaround a perimeter of the electrochemical cell.

Embodiment 127 provides the method of any one of Embodiments 3-126,wherein the conductive connector comprises a screw, a bolt, a nut, awasher, or a combination thereof.

Embodiment 128 provides the method of any one of Embodiments 3-127,wherein the conductive connector comprises a screw or a bolt.

Embodiment 129 provides the method of any one of Embodiments 1-128,wherein the electrochemical cell comprises a plurality of the cathodes.

Embodiment 130 provides the method of any one of Embodiments 1-129,wherein the electrochemical cell comprises a plurality of the anodes.

Embodiment 131 provides the method of any one of Embodiments 1-130,wherein a ratio of anode surface area to cathode surface area for theelectrochemical cell is about 0.1 to about 10.

Embodiment 132 provides the method of any one of Embodiments 1-131,wherein a ratio of anode surface area to cathode surface area for theelectrochemical cell is about 0.5 to about 2.

Embodiment 133 provides the method of any one of Embodiments 1-132,wherein the cathode comprises a roughened or etched surface.

Embodiment 134 provides the method of any one of Embodiments 1-133,wherein the conductivity of the water comprising the phosphorus duringimmersion of the electrochemical cell in the water comprising thephosphorus is about 100 μS to about 1,000,000 μS.

Embodiment 135 provides the method of any one of Embodiments 1-134,wherein the conductivity of the water comprising the phosphorus duringimmersion of the electrochemical cell in the water comprising thephosphorus is about 300 μS to about 100,000 μS.

Embodiment 136 provides the method of any one of Embodiments 1-135,further comprising regulating conductivity of the water comprising thephosphorus such that the conductivity is about 100 μS to about 1,200 μS.

Embodiment 137 provides the method of Embodiment 136, wherein regulatingthe conductivity of the water comprising the phosphorus comprisesregulating a rate of introduction of fresh water comprising thephosphorus to the electrochemical cell.

Embodiment 138 provides the method of any one of Embodiments 136-137,wherein regulating the conductivity of the water comprising thephosphorus comprises adding one or more salts to the water comprisingthe phosphorus.

Embodiment 139 provides the method of any one of Embodiments 136-138,wherein the salt is added to the water comprising the phosphorus beforeimmersing the electrochemical cell in the water comprising phosphorus,during the immersion of the electrochemical cell in the water comprisingphosphorus, after the immersion of the electrochemical cell in the watercomprising phosphorus, or a combination thereof.

Embodiment 140 provides the method of any one of Embodiments 136-139,wherein the one or more salts added to the water comprising phosphorusto regulate the conductivity thereof comprise halogen salts, sodiumsalts, potassium salts, or a combination thereof.

Embodiment 141 provides the method of any one of Embodiments 136-140,wherein the one or more salts added to the water comprising phosphorusto regulate the conductivity thereof comprise sodium chloride.

Embodiment 142 provides the method of any one of Embodiments 1-141,wherein the electrochemical cell comprises a spacing between a surfaceof the anode and a surface of the cathode of about 1 mm to about 110 mm.

Embodiment 143 provides the method of Embodiment 142, wherein theelectrochemical cell comprises the spacing of about 1 mm to about 110 mmbetween the cathode and at least about 80% of the total surface area ofthe anode.

Embodiment 144 provides the method of any one of Embodiments 142-143,wherein the electrochemical cell comprises a spacing between a surfaceof the anode and a surface of the cathode of about 2 mm to about 30 mm.

Embodiment 145 provides the method of any one of Embodiments 1-144,wherein the water comprising phosphorus is water taken from a sourcecomprising a natural source of water in the environment, drinking water,industrial waste-water, industrial cooling water, or a combinationthereof.

Embodiment 146 provides the method of any one of Embodiments 1-145,wherein the water comprising phosphorus is water taken from a sourcecomprising a natural source of water in the environment.

Embodiment 147 provides the method of any one of Embodiments 1-146,wherein the method is free of treating the water comprising thephosphorus with an oxidizer or an oxidative treatment other than anyoxidation that occurs due to immersion of the electrochemical cell inthe water comprising the phosphorus.

Embodiment 148 provides the method of any one of Embodiments 1-147,further comprising oxidizing phosphorus in the water comprising thephosphorus prior to the immersion of the electrochemical cell in thewater comprising phosphorus, during the immersion of the electrochemicalcell in the water comprising phosphorus, or a combination thereof.

Embodiment 149 provides the method of Embodiment 148, wherein theimmersing of the electrochemical cell in the water comprising thephosphorus is sufficient to oxidize the phosphorus in the watercomprising the phosphorus.

Embodiment 150 provides the method of any one of Embodiments 148-149,comprising oxidizing phosphorus in the water comprising the phosphorusprior to the immersion of the electrochemical cell in the watercomprising phosphorus.

Embodiment 151 provides the method of Embodiment 150, wherein oxidizingthe phosphorus in the water comprising the phosphorus comprisescontacting an oxidizer and the water comprising phosphorus to oxidizethe phosphorus.

Embodiment 152 provides the method of any one of Embodiments 150-151,wherein an aqueous solution of the oxidizer is added to the watercomprising phosphorus.

Embodiment 153 provides the method of any one of Embodiments 150-152,wherein the aqueous solution of the oxidizer has a concentration of theoxidizer of about 0.001 ppm to about 999,999 ppm.

Embodiment 154 provides the method of any one of Embodiments 150-153,wherein the aqueous solution of the oxidizer has a concentration of theoxidizer of about 50,000 ppm to about 140,000 ppm.

Embodiment 155 provides the method of any one of Embodiments 150-154,wherein the oxidizer comprises ferrate, ozone, ferric chloride (FeCl₃),potassium permanganate, potassium dichromate, potassium chlorate,potassium persulfate, sodium persulfate, perchloric acid, peraceticacid, potassium monopersulfate, hydrogen peroxide, sodium hypochlorite,potassium hypochlorite, hydroxide, sulfite, a free radical viadecomposition thereof, or a combination thereof.

Embodiment 156 provides the method of any one of Embodiments 150-155,wherein the oxidizer converts substantially all dissolved phosphorus inthe water comprising the phosphorus into oxidized forms of phosphorus.

Embodiment 157 provides the method of any one of Embodiments 1-156,further comprising adjusting the pH of the separated water to be about 6to about 8.

Embodiment 158 provides the method of any one of Embodiments 1-157,further comprising adjusting the pH of the separated water to be about7.

Embodiment 159 provides the method of any one of Embodiments 1-158,wherein the method is free of pH treatment of the separated water.

Embodiment 160 provides the method of any one of Embodiments 1-159,wherein the method comprises immersing a plurality of theelectrochemical cells in the water comprising the phosphorus.

Embodiment 161 provides the method of any one of Embodiments 1-160,wherein the electrochemical cell is planar.

Embodiment 162 provides the method of any one of Embodiments 1-161,wherein the electrochemical cell has a thickness that is less than aheight and a width of the electrochemical cell.

Embodiment 163 provides the method of any one of Embodiments 1-162,wherein the cathode comprises a planar frame of the electrochemical celland a cathode material comprised within a perimeter of the frame,wherein the cathode material is electrically connected to the frame.

Embodiment 164 provides the method of Embodiment 163, wherein the frameis a structural component of the electrochemical cell, the framecomprising the cathode material, wherein the frame is structurallysufficient to maintain its shape in the absence of any of or all of theanodes.

Embodiment 165 provides the method of any one of Embodiments 163-164,wherein the planar frame is nonporous solid material.

Embodiment 166 provides the method of any one of Embodiments 163-165,wherein the planar frame is one or more strips of cathode material.

Embodiment 167 provides the method of any one of Embodiments 163-166,wherein the planar frame has a polygonal perimeter.

Embodiment 168 provides the method of any one of Embodiments 163-167,wherein the planar frame is a square or rectangle.

Embodiment 169 provides the method of any one of Embodiments 163-168,wherein the cathode material comprised within the perimeter of theplanar frame comprises a porous cathode material.

Embodiment 170 provides the method of Embodiment 169, wherein the porouscathode material comprises wire, mesh, screen, a sheet comprising one ormore through-holes, or a combination thereof.

Embodiment 171 provides the method of Embodiment 170, wherein the porouscathode material comprises a wire mesh or a wire screen comprising theporous cathode material.

Embodiment 172 provides the method of any one of Embodiments 170-171,wherein the electrochemical cell further comprises a conductiveconnector that electrically connects the anode and the cathode, theconductive connector comprising Cu, Zn, Fe, Cd, Ni, Sn, Pb, or acombination thereof, wherein the porous cathode material comprisedwithin the perimeter of the planar frame has edges that are sandwichedbetween two of the planar frames, the two planar frames held together tosecure the porous cathode material therebetween with one or more of theconductive connectors.

Embodiment 173 provides the method of Embodiment 172, wherein theelectrochemical cell comprises a plurality of pairs of the planarframes, each pair held together to secure the porous cathode materialtherebetween with one or more of the conductive connectors, and eachpair separated by one or more of the anodes spanning across the porouscathode material comprised within the perimeter of the planar frame.

Embodiment 174 provides the method of Embodiment 173, wherein the one ormore anodes that separate each pair of planar frames from one anotherdirectly contact a face of each pair of planar frames separatedtherewith.

Embodiment 175 provides the method of any one of Embodiments 173-174,wherein the one or more anodes that separate each pair of planar framesfrom one another directly contact a face of one of each pair of planarframes separated therewith and are free of direct contact with a face ofthe other of each pair of planar frames separated therewith.

Embodiment 176 provides the method of any one of Embodiments 170-175,wherein the electrochemical cell further comprises a conductiveconnector that electrically connects the anode and the cathode, theconductive connector comprising Cu, Zn, Fe, Cd, Ni, Sn, Pb, or acombination thereof, wherein the anode is a strip fastened to the planarframe at two edges of the planar frame, wherein the anode is fastened tothe planar frame with at least one of the conductive connectors at eachof the two edges of the planar frame, such that the anode spans acrossthe cathode material comprised within the perimeter of the planar frameforming a gap between the cathode material comprised within theperimeter of the planar frame and the anode strip.

Embodiment 177 provides the method of Embodiment 176, wherein the anodeand the cathode directly contact one another at each of the edges of theplanar frame where the anode is fastened to the planar frame via the atleast one conductive connector.

Embodiment 178 provides the method of any one of Embodiments 170-177,wherein the electrochemical cell further comprises a conductiveconnector that electrically connects the anode and the cathode, theconductive connector comprising Cu, Zn, Fe, Cd, Ni, Sn, Pb, or acombination thereof, wherein the electrochemical cell comprises aplurality of the anodes, wherein each anode is a strip fastened to theplanar frame at two edges of the planar frame on a face of the frame,wherein each of the anodes is fastened to the planar frame with at leastone of the conductive connectors at each of the two edges of the planarframe, such that each of the anodes spans across the cathode materialcomprised within the perimeter of the planar frame forming a gap betweenthe cathode material comprised within the perimeter of the planar frameand the anode strip, wherein the plurality of the anodes arespaced-apart across the face of the such that they do not physicallycontact one another.

Embodiment 179 provides the method of Embodiment 178, wherein each ofthe anodes spans across the cathode material comprised within theperimeter of the planar frame approximately parallel to one another onthe face.

Embodiment 180 provides the method of any one of Embodiments 178-179,wherein the two edges of the planar frame to which are fastened eachanode are opposite edges of the planar frame.

Embodiment 181 provides the method of any one of Embodiments 178-180,wherein all of the anodes are on a single major face of the planarframe.

Embodiment 182 provides the method of any one of Embodiments 178-181,wherein some of the anodes are on one major face of the planar frame,and the other anodes are on another major face of the frame.

Embodiment 183 provides the method of any one of Embodiments 3-182,wherein the electrochemical cell comprises the cathode, wherein thecathode comprises a planar frame of the electrochemical cell having apolygonal perimeter and a porous material comprised within the perimeterof the frame that is a wire mesh or a wire screen that is in directcontact with the frame; a plurality of the anodes, wherein each anode isa strip fastened to the planar frame at two opposite edges of the planarframe on a face of the planar frame, wherein each of the anodes isfastened to the planar frame with at least one of the conductiveconnectors at each of the two edges of the planar frame, such that eachof the anodes are approximately parallel to one another and span acrossthe porous material comprised within the perimeter of the planar frameforming a gap between the porous material comprised within the perimeterof the planar frame and the anode strip, wherein each anode directlycontacts the cathode frame at each of the edges of the planar framewhere the anode is fastened to the planar frame via the at least oneconductive connector, wherein the plurality of the anodes arespaced-apart across the face of the such that they do not physicallycontact one another, and wherein the gap is about 1 mm to about 110 mm.

Embodiment 184 provides the method of any one of Embodiments 1-183,comprising

immersing one or more of the electrochemical cells in an enclosurecomprising the water comprising the phosphorus;

filtering the salt comprising the phosphorus from the treated water viaone of more filters that are at least partially submerged in the watercomprising the phosphorus that immerses the electrochemical cells.

Embodiment 185 provides the method of Embodiment 184, wherein the filtercomprises a glass frit, a fabric filter, a paper filter, a disk filter,a rotary filter, a drum filter, a screen, a sieve, particulatefiltration media, a filter aid, or a combination thereof.

Embodiment 186 provides the method of any one of Embodiments 184-185,wherein the filter is a rotating disk filter.

Embodiment 187 provides the method of any one of Embodiments 184-186,wherein the filtering comprises forming a filter cake on the filter, thefilter cake comprising the salt comprising the phosphorus.

Embodiment 188 provides the method of Embodiment 187, further comprisingbackwashing the filter to remove the filter cake from the filter and toform a backwash liquor that comprises the removed filter cake.

Embodiment 189 provides the method of Embodiment 188, wherein a portionof the water comprising the precipitate is used to backwash the filter.

Embodiment 190 provides the method of any one of Embodiments 184-189,wherein the one or more electrochemical cells are positioned in thewater comprising the phosphorus at side portions of the enclosure,wherein the filter is positioned approximately in a central portion ofthe enclosure in the water comprising the phosphorus such that thefilter is in-between the plurality of electrochemical cells.

Embodiment 191 provides the method of any one of Embodiments 184-190,comprising a plurality of the filters.

Embodiment 192 provides the method of Embodiment 191, wherein the one ormore filters comprise a plurality of rotating disk filters.

Embodiment 193 provides a method of removing phosphorus from water, themethod comprising:

immersing an electrochemical cell in water comprising phosphorus havinga pH of about 5 to about 7 to form treated water comprising a salt thatcomprises the phosphorus, the salt comprising

-   -   AlPO₄ or a hydrate thereof, the AlPO₄ comprising the phosphorus        and Al from the anode,    -   aluminum hydroxide or a hydrate thereof, the aluminum hydroxide        comprising Al from the anode, or    -   a combination thereof,

the electrochemical cell comprising

-   -   an anode comprising Al, wherein the anode is about 90 wt % to        about 100 wt % Al,    -   a cathode comprising Cu, wherein the cathode is about 90 wt % to        about 100 wt % Cu, and    -   a conductive connector that electrically connects the anode and        the cathode, the conductive connector comprising an alloy        comprising Cu and Zn; and

separating the salt comprising the phosphorus from the treated water, toform separated water having a lower phosphorus concentration than thewater comprising phosphorus.

Embodiment 194 provides a method of removing phosphorus from water, themethod comprising:

immersing an electrochemical cell in water comprising phosphorus havinga pH of about 10 to about 11 to form treated water comprising a saltthat comprises the phosphorus, the salt comprising

-   -   magnesium phosphate, magnesium potassium phosphate, a hydrate        thereof, or a combination thereof,    -   NH₄MgPO₄ or a hydrate thereof, the NH₄MgPO₄ comprising the        phosphorus and Mg from the anode,    -   Mg(OH)₂ comprising Mg from the anode, or    -   a combination thereof,

the electrochemical cell comprising

-   -   an anode comprising Mg, wherein the anode is about 90 wt % to        about 100 wt % Mg,    -   a cathode comprising Cu, wherein the cathode is about 90 wt % to        about 100 wt % Cu, and    -   a conductive connector that electrically connects the anode and        the cathode, the conductive connector comprising an alloy        comprising Cu and Zn; and

separating the salt comprising the phosphorus from the treated water, toform separated water having a lower phosphorus concentration than thewater comprising phosphorus.

Embodiment 195 provides an electrochemical cell for performing themethod of any one of Embodiments 1-194, the electrochemical cellcomprising:

a cathode comprising Cu, Ni, Fe, or a combination thereof, wherein thecathode comprises a planar frame of the electrochemical cell having apolygonal perimeter and a porous material comprised within the perimeterof the frame that is a wire mesh or a wire screen that is in directcontact with the frame; and

a plurality of anodes comprising Mg, Al, Fe, Zn, or a combinationthereof, and a plurality of conductive connectors that electricallyconnect the anode and the cathode, the conductive connector comprisingCu, Zn, Fe, Cd, Ni, Sn, Pb, or a combination thereof,

wherein each anode is a strip fastened to the planar frame at twoopposite edges of the planar frame on a face of the frame, wherein eachof the anodes is fastened to the planar frame with at least one of theconductive connectors at each of the two edges of the planar frame, suchthat each of the anodes on the face are approximately parallel to oneanother on the face and span across the porous material comprised withinthe perimeter of the planar frame forming a gap between the porousmaterial comprised within the perimeter of the planar frame and theanode strip, wherein each anode directly contacts the cathode frame ateach of the edges of the planar frame where the anode is fastened to theplanar frame via the at least one conductive connector, wherein theplurality of the anodes are spaced-apart across the face of the suchthat they do not physically contact one another, and wherein the gap isabout 1 mm to about 110 mm.

Embodiment 196 provides a method of making struvite, the methodcomprising:

immersing an electrochemical cell in water comprising phosphorus havinga pH of about 10 to about 11 to form treated water comprising a saltthat comprises the phosphorus, the salt comprising struvite, thestruvite comprising the phosphorus and Mg from the anode, theelectrochemical cell comprising

-   -   an anode comprising Mg, wherein the anode is about 90 wt % to        about 100 wt % Mg,    -   a cathode comprising Cu, wherein the cathode is about 90 wt % to        about 100 wt % Cu; and

separating the salt comprising the phosphorus from the treated water toobtain separated struvite and to form separated water having a lowerphosphorus concentration than the water comprising phosphorus.

Embodiment 197 provides the method of Embodiment 196, wherein theelectrochemical cell further comprises a conductive connector thatelectrically connects the anode and the cathode, the conductiveconnector comprising Cu, Zn, Fe, Cd, Ni, Sn, Pb, or a combinationthereof.

Embodiment 198 provides the method of any one of Embodiments 196-197,wherein the anode and the cathode directly contact one another.

Embodiment 199 provides the method of any one of Embodiments 196-198,further comprising purifying the separated struvite.

Embodiment 200 provides the method of any one of Embodiments 196-199,wherein the water comprising the phosphorus further comprises nitrogen.

Embodiment 201 provides the method of Embodiment 200, further comprisingadding the nitrogen to the water comprising the phosphorus.

Embodiment 202 provides the method of Embodiment 201, wherein thenitrogen added to the water comprising the phosphorus is added as KNO₃,HNO₃, an organic nitrogen compound, or a combination thereof.

Embodiment 203 provides the method of any one of Embodiments 196-202,further comprising adding phosphorus to water to form the watercomprising the phosphorus.

Embodiment 204 provides a method of making APO₄, aluminum hydroxide, ora combination thereof, the method comprising:

immersing an electrochemical cell in water comprising phosphorus havinga pH of about 5 to about 7 to form treated water comprising a salt thatcomprises the phosphorus, the salt comprising

-   -   AlPO₄ or a hydrate thereof, the AlPO₄ comprising the phosphorus        and Al from the anode,    -   aluminum hydroxide or a hydrate thereof, the aluminum hydroxide        comprising Al from the anode, or    -   a combination thereof,

the electrochemical cell comprising

-   -   an anode comprising Al, wherein the anode is about 90 wt % to        about 100 wt % Al,    -   a cathode comprising Cu, wherein the cathode is about 90 wt % to        about 100 wt % Cu; and

separating the salt comprising the phosphorus from the treated water, toform separated water having a lower phosphorus concentration than thewater comprising phosphorus.

Embodiment 205 provides the method of Embodiment 204, wherein theelectrochemical cell further comprises a conductive connector thatelectrically connects the anode and the cathode, the conductiveconnector comprising Cu, Zn, Fe, Cd, Ni, Sn, Pb, or a combinationthereof.

Embodiment 206 provides the method of any one of Embodiments 204-205,wherein the anode and the cathode directly contact one another.

Embodiment 207 provides the method of any one of Embodiments 204-206,further comprising adding phosphorus to water to form the watercomprising the phosphorus.

Embodiment 208 provides the method of any one of Embodiments 204-207,further comprising purifying the salt comprising the phosphorus, toprovide purified AlPO₄, purified aluminum hydroxide, or a purifiedmixture of AlPO₄ and aluminum hydroxide.

Embodiment 209 provides a method of making magnesium phosphate, Mg(OH)₂,or a combination thereof, the method comprising:

immersing an electrochemical cell in water comprising phosphorus havinga pH of about 10 to about 11 to form treated water comprising a saltthat comprises the phosphorus, the salt comprising

-   -   magnesium phosphate, magnesium potassium phosphate, a hydrate        thereof, or a combination thereof,    -   Mg(OH)₂ comprising Mg from the anode, or    -   a combination thereof,

the electrochemical cell comprising

-   -   an anode comprising Mg, wherein the anode is about 90 wt % to        about 100 wt % Mg,    -   a cathode comprising Cu, wherein the cathode is about 90 wt % to        about 100 wt % Cu; and

separating the salt comprising the phosphorus from the treated water, toform separated water having a lower phosphorus concentration than thewater comprising phosphorus.

Embodiment 210 provides the method of Embodiment 209, wherein theelectrochemical cell further comprises a conductive connector thatelectrically connects the anode and the cathode, the conductiveconnector comprising Cu, Zn, Fe, Cd, Ni, Sn, Pb, or a combinationthereof.

Embodiment 211 provides the method of any one of Embodiments 209-210,wherein the anode and the cathode directly contact one another.

Embodiment 212 provides the method of any one of Embodiments 209-211,further comprising adding phosphorus to water to form the watercomprising phosphorus.

Embodiment 213 provides the method of any one of Embodiments 209-212,further comprising purifying the salt comprising the phosphorus, toprovide purified magnesium phosphate, purified Mg(OH)₂, or a purifiedmixture of magnesium phosphate and Mg(OH)₂.

Embodiment 214 provides a method of removing one or more dissolvedtransition metals, post-transition metals, or metalloids from water, themethod comprising:

immersing an electrochemical cell in water comprising the one or moredissolved transition metals, post-transition metals, or metalloids toform treated water comprising a hydroxide salt that comprises the one ormore transition metals, post-transition metals, or metalloids, theelectrochemical cell comprising

-   -   an anode comprising Mg, Al, Fe, Zn, or a combination thereof,    -   a cathode having a different composition than the anode, the        cathode comprising Cu, Ni, Fe, or a combination thereof, and

separating the salt comprising the hydroxide salt that comprises the oneor more transition metals, post-transition metals, or metalloids, toform separated water having a lower concentration of the one or moretransition metals, post-transition metals, or metalloids than the watercomprising the one or more transition metals, post-transition metals, ormetalloids.

Embodiment 215 provides the method of Embodiment 214, wherein theelectrochemical cell further comprises a conductive connector thatelectrically connects the anode and the cathode, the conductiveconnector comprising Cu, Zn, Fe, Cd, Ni, Sn, Pb, or a combinationthereof.

Embodiment 216 provides the method of any one of Embodiments 214-215,wherein the anode and the cathode directly contact one another.

Embodiment 217 provides the method of any one of Embodiments 214-215,wherein the one or more transition metals, post-transition metals, ormetalloids comprise Sc, Y, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo,Tc, Ru, Rh, Pd, Ag, Hf, Ta, W, Re, Os, Ir, Pt, Au, Rf, Db, Sg, Bh, Hs,Al, Zn, Ga, Cd, In, Sn, Hg, Tl, Pb, Bi, Po, Cn, B, Si, Ge, As, Sb, Te,At, or a combination thereof.

Embodiment 218 provides the method of any one of Embodiments 214-216,wherein the one or more transition metals, post-transition metals, ormetalloids comprise Hg, Fe, Cr, Ni, Zn, Cd, As, or a combinationthereof.

Embodiment 219 provides the method of any one of Embodiments 214-217,wherein the separated water has a concentration of the transition metal,post-transition metal, metalloid, or combination thereof, that is about0% to about 70% of a concentration of the transition metal,post-transition metal, metalloid, or combination thereof, in the watercomprising the one or more dissolved transition metals, post-transitionmetals, or metalloids.

Embodiment 220 provides the method of any one of Embodiments 214-218,wherein the separated water has a concentration of the transition metal,post-transition metal, metalloid, or combination thereof, that is about0% to about 20% of a concentration of the transition metal,post-transition metal, metalloid, or combination thereof, in the watercomprising the one or more dissolved transition metals, post-transitionmetals, or metalloids.

Embodiment 219 provides the method or electrochemical cell of any one orany combination of Embodiments 1-218 optionally configured such that allelements or options recited are available to use or select from.

What is claimed is:
 1. A method of removing phosphorus from water, themethod comprising: immersing an electrochemical cell in water comprisingphosphorus to form treated water comprising a salt that comprises thephosphorus, wherein the electrochemical cell is a galvanic cell, theelectrochemical cell comprising an anode comprising Al, a cathode havinga different composition than the anode, the cathode comprising Cu,wherein the cathode comprises a planar frame of the electrochemical celland a cathode material comprised within a perimeter of the frame,wherein the cathode material is electrically connected to the frame,wherein the cathode material comprised within the perimeter of theplanar frame comprises a porous cathode material, and a conductiveconnector that electrically connects the anode and the cathode, theconductive connector comprising Cu, Zn, Fe, Cd, Ni, Sn, Pb, or acombination thereof, wherein the conductive connector comprises a screw,a bolt, or a combination thereof; and separating the salt comprising thephosphorus from the treated water, to form separated water having alower phosphorus concentration than the water comprising phosphorus. 2.The method of claim 1, wherein the anode and the cathode directlycontact one another.
 3. The method of claim 1, wherein the conductiveconnector comprises an alloy comprising Cu and Zn.
 4. The method ofclaim 1, wherein the conductive connector comprises brass.
 5. The methodof claim 1, wherein the separated water has a total phosphorusconcentration that is 0% to 20% of the total phosphorus concentration ofthe water comprising phosphorus, or has a dissolved phosphorusconcentration that is 0% to 20% of the dissolved phosphorusconcentration of the water comprising phosphorus, or has a reactivephosphorus concentration that is 0% to 20% of the total phosphorusconcentration of the water comprising phosphorus, or has a totalnitrogen concentration that is 0% to 30% of a total nitrogenconcentration of the water comprising phosphorus, or has a totalnitrogen concentration that is 0% to 30% of a dissolved nitrogenconcentration of the water comprising phosphorus, or a combinationthereof.
 6. The method of claim 1, wherein the salt comprising thephosphorus comprises a material from the anode.
 7. The method of claim1, wherein the water comprising phosphorus further comprises a dissolvedtransition metal, post-transition metal, metalloid, or a combinationthereof, further comprising forming a hydroxide salt comprising thetransition metal, post-transition metal, or metalloid during theimmersing of the electrochemical cell in the water comprisingphosphorus, wherein the separating of the salt comprising the phosphorusfrom the treated water further comprises separating the hydroxide saltcomprising the transition metal, post-transition metal, or metalloidfrom the treated water.
 8. The method of claim 1, further comprisingapplying mechanical force to the electrochemical cell during theimmersing of the electrochemical cell in the water comprisingphosphorus, or applying shear to the water comprising phosphorus duringthe immersing of the electrochemical cell in the water comprisingphosphorus, or a combination thereof, wherein the mechanical forceand/or shear is sufficient to dislodge at least some bubbles comprisingH₂ from the surface of the anode, cathode, or a combination thereof, orat least partially prevent oxide formation at the surface of the anode,or at least partially prevent agglomeration of the salt comprising thephosphorus on the surface of the anode, or a combination thereof.
 9. Themethod of claim 1, comprising immersing the electrochemical cell or aplurality thereof in an enclosure comprising the water comprising thephosphorus; and filtering the salt comprising the phosphorus from thetreated water via one of more filters that are at least partiallysubmerged in the water comprising the phosphorus that immerses theelectrochemical cells.
 10. The method of claim 1, wherein theelectrochemical cell comprises: the planar frame, wherein the planarframe comprises a polygonal perimeter; the porous cathode material,wherein the porous cathode material comprises a wire mesh or a wirescreen that is in direct contact with the frame; and a plurality ofanodes that are each the anode comprising Al, and a plurality of theconductive connectors that electrically connect each of the anodes andthe cathode; wherein each of the anodes is a strip fastened to theplanar frame at two opposite edges of the planar frame on a face of theframe, wherein each of the anodes is fastened to the planar frame withat least one of the conductive connectors at each of the two edges ofthe planar frame, such that each of the anodes on the face areapproximately parallel to one another on the face and span across theporous material comprised within the perimeter of the planar frameforming a gap between the porous material comprised within the perimeterof the planar frame and the anode strip, wherein each of the anodesdirectly contacts the cathode frame at each of the edges of the planarframe, wherein the plurality of the anodes are spaced-apart across theface of the frame such that they do not physically contact one another,and wherein the gap is about 1 mm to about 110 mm.
 11. The method ofclaim 1, wherein the method is a method of making AlPO₄, aluminumhydroxide, or a combination thereof, wherein: the water comprisingphosphorus has a pH of about 5 to about 7; the salt comprising thephosphorus comprises AlPO₄ or a hydrate thereof, the AlPO₄ comprisingthe phosphorus and Al from the anode, or aluminum hydroxide or a hydratethereof, the aluminum hydroxide comprising Al from the anode, or acombination thereof; the anode is about 90 wt % to about 100 wt % Al;the cathode is about 90 wt % to about 100 wt % Cu; and separating thesalt comprising the phosphorus from the treated water provides separatedAlPO₄, aluminum hydroxide, or a combination thereof.
 12. A method ofremoving phosphorus froth water, the method comprising: immersing anelectrochemical cell in water comprising phosphorus having a pH of about5 to about 7 to form treated water comprising a salt that comprises thephosphorus, wherein the electrochemical cell is a galvanic cell, thesalt comprising AlPO₄ or a hydrate thereof, the AIM comprising thephosphorus and Al from the anode, aluminum hydroxide or a hydratethereof, the aluminum hydroxide comprising Al from the anode, or acombination thereof, the electrochemical cell comprising an anodecomprising Al, wherein the anode is about 90 wt % to about 100 wt % Al,a cathode comprising Cu, wherein the cathode is about 90 wt % to about100 wt % Cu, wherein the cathode comprises a planar frame of theelectrochemical cell and a cathode material comprised within a perimeterof the frame, wherein the cathode material is electrically connected tothe frame, wherein the cathode material comprised within the perimeterof the planar frame comprises a porous cathode material, and aconductive connector that electrically connects the anode and thecathode, the conductive connector comprising an alloy comprising Cu andZn, wherein the conductive connector comprises a screw, a bolt, or acombination thereof; and separating the salt comprising the phosphorusfrom the treated water, to form separated water having a lowerphosphorus concentration than the water comprising phosphorus.
 13. Amethod of removing phosphorus from water, the method comprising:immersing an electrochemical cell in water comprising phosphorus to formtreated water comprising a salt that comprises the phosphorus, theelectrochemical cell comprising an anode comprising Mg, Al, Fe, Zn, or acombination thereof, a cathode having a different composition than theanode, the cathode comprising Cu, Ni, Fe, or a combination thereof; andseparating the salt comprising the phosphorus from the treated water, toform separated water having a lower phosphorus concentration than thewater comprising phosphorus; wherein the electrochemical cell comprisesthe cathode comprising Cu, Ni, Fe, or a combination thereof, wherein thecathode comprises a planar frame of the electrochemical cell having apolygonal perimeter and a porous material comprised within the perimeterof the frame that is a wire mesh or a wire screen that is in directcontact with the frame, and a plurality of anodes that are each theanode comprising Mg, Al, Fe, Zn, or a combination thereof, and aplurality of conductive connectors that electrically connect each of theanodes and the cathode, each of the conductive connectors comprising Cu,Zn, Fe; Cd, Ni, Sn, Pb, or a combination thereof, wherein each of theanodes is a strip fastened to the planar frame at two opposite edges ofthe planar frame on a face of the frame, wherein each of the anodes isfastened to the planar frame with at least one of the conductiveconnectors at each of the two edges of the planar frame, such that eachof the anodes on the face are approximately parallel to one another onthe face and span across the porous material comprised within theperimeter of the planar frame forming a gap between the porous materialcomprised within the perimeter of the planar frame and the anode strip,wherein each of the anodes directly contacts the cathode frame at eachof the edges of the planar frame, wherein the plurality of the anodesare spaced-apart across the face of the such that they do not physicallycontact one another, and wherein the gap is about 1 mm to about 110 mm.14. A method of removing phosphorus from water, the method comprising:immersing an electrochemical cell in water comprising phosphorus to formtreated water comprising a salt that comprises the phosphorus, whereinthe electrochemical cell is a galvanic cell, the electrochemical cellcomprising a plurality of anodes in the form of strips, each of theanodes comprising Al, a cathode having a different composition than theanode, the cathode comprising Cu, and a plurality of conductiveconnectors, each of the conductive connectors comprising Cu Zn Fe, Cd,Ni, Sn, Pb, or a combination thereof, wherein each of the conductiveconnectors comprises a screw, a bolt, or a combination thereof, andwherein each anode is fastened to and electrically connected to thecathode via at least one of the conductive connectors; and separatingthe salt comprising the phosphorus from the treated water, to formseparated water having a lower phosphorus concentration than the watercomprising phosphorus.